Dynamic reliability networks with self-healing units

International Nuclear Information System (INIS)

Jenab, K.; Seyed Hosseini, S.M.; Dhillon, B.S.

2008-01-01

This paper presents an analytical approach for dynamic reliability networks used for the failure limit strategy in maintenance optimization. The proposed approach utilizes the moment generating function (MGF) and the flow-graph concept to depict the functional and reliability diagrams of the system comprised of series, parallel or mix configuration of self-healing units. The self-healing unit is featured by the embedded failure detection and recovery mechanisms presented by self-loop in flow-graph networks. The newly developed analytical approach provides the probability of the system failure and time-to-failure data i.e., mean and standard deviation time-to-failure used for maintenance optimization

Self-Healing Corrosion Protective Sol-Gel Coatings

NARCIS (Netherlands)

Abdolah Zadeh, M.

2016-01-01

Inspired by the state of the art and the recent advances in the field of self-healing corrosion protective coatings, the thesis entitled “Self-healing corrosion protective sol-gel coatings” addresses novel routes to self-healing corrosion protective sol-gel coatings via extrinsic and intrinsic

Evaluating Self Healing Capability of Bituminous Mastics

NARCIS (Netherlands)

Qiu, J.; Van de Ven, M.; Wu, S.; Yu, J.; Molenaar, A.

2012-01-01

The self-healing capability of bituminous materials has been known for many years. Researches were mostly focused on the self healing behaviour during load repetitions. The tests are either time consuming and/or complex. In this paper, a simple self healing test procedure is presented combining the

Self-healing Coatings for an Anti-corrosion barrier in Damaged Parts

International Nuclear Information System (INIS)

Cho, Soo Hyoun

2009-01-01

Polymer coatings are commonly applied to metal substrates to prevent corrosion in aggressive environments such as high humidity and under salt water. Once the polymer coating has been breached, for example due to cracking or scratches, it loses its effectiveness, and corrosion can rapidly propagate across the substrate. The self-healing system we will describe prevents corrosion by healing the damage through a healing reaction triggered by the actual damage event. This self-healing coating solution can be easily applied to most substrate materials, and our dual-capsule healing system provides a general approach to be compatible with most common polymer matrices. Specifically, we expect an excellent anti-corrosion property of the self-healing coatings in damaged parts coated on galvanized metal substrates.

Solid State Self-Healing System: Effects of Using Immiscible Healing Agents

International Nuclear Information System (INIS)

Noor Nabilah Muhamad; Mohd Suzeren Mohd Jamil

2015-01-01

The solid state self-healing system was obtained by employs a thermosetting epoxy resin, into which a thermoplastic is dissolved. The aim of this study is to identify the effect of using immiscible healing agents, which are polyvinyl chloride and polyvinyl alcohol, on solid state self-healing system. Healing was achieved by heating the fractured resins to a specific temperature; above their glass transition temperature (Tg) which obtained from dynamic mechanical analysis (DMA) in order for thermal expansion to occur. The thermal properties and bonding formed in the epoxy resins were characterized by means of Fourier Transform Infrared Spectroscopy (FTIR). Izod impact test was performed in preliminary work. Further work then has been done using compact tension test to demonstrate details self-healing capability of the different specimens. Under compact tension test, it was found that healable resin with PVC has highest healing efficiency followed PVA with 7.4 % and 3 % of average percentage healing efficiencies respectively. These results are due to the different solubility parameters of the thermoset/ network and thermoplastic polymer which led to the phase separation. Morphological studies using microscope optic prove the fracture-healing process and morphological properties of the resins. (author)

Lap shear strength and healing capability of self-healing adhesive containing epoxy/mercaptan microcapsules

Energy Technology Data Exchange (ETDEWEB)

Ghazali, Habibah; Ye, Lin [Centre for Advanced Materials Technology (CAMT), School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Zhang, Ming-Qiu [Key Laboratory of Polymeric Composite and Functional Materials of Ministry of Education, Zhongshan University, Guangzhou 510275 (China)

2016-03-09

The aim of this work is to develop a self-healing polymeric adhesive formulation with epoxy/mercaptan microcapsules. Epoxy/mercaptan microcapsules were dispersed into a commercialize two-part epoxy adhesive for developing self-healing epoxy adhesive. The influence of different content of microcapsules on the shear strength and healing capability of epoxy adhesive were investigated using single-lap-joints with average thickness of adhesive layer of about 180 µm. This self-healing adhesive was used in bonding of 5000 series aluminum alloys adherents after mechanical and alkaline cleaning surface treatment. The adhesion strength was measured and presented as function of microcapsules loading. The results indicated that the virgin lap shear strength was increased by about 26% with addition of 3 wt% of self-healing microcapsules. 12% to 28% recovery of the shear strength is achieved after self-healing depending on the microcapsules content. Scanning electron microscopy was used to study fracture surface of the joints. The self-healing adhesives exhibit recovery of both cohesion and adhesion properties with room temperature healing.

Lap shear strength and healing capability of self-healing adhesive containing epoxy/mercaptan microcapsules

International Nuclear Information System (INIS)

Ghazali, Habibah; Ye, Lin; Zhang, Ming-Qiu

2016-01-01

The aim of this work is to develop a self-healing polymeric adhesive formulation with epoxy/mercaptan microcapsules. Epoxy/mercaptan microcapsules were dispersed into a commercialize two-part epoxy adhesive for developing self-healing epoxy adhesive. The influence of different content of microcapsules on the shear strength and healing capability of epoxy adhesive were investigated using single-lap-joints with average thickness of adhesive layer of about 180 µm. This self-healing adhesive was used in bonding of 5000 series aluminum alloys adherents after mechanical and alkaline cleaning surface treatment. The adhesion strength was measured and presented as function of microcapsules loading. The results indicated that the virgin lap shear strength was increased by about 26% with addition of 3 wt% of self-healing microcapsules. 12% to 28% recovery of the shear strength is achieved after self-healing depending on the microcapsules content. Scanning electron microscopy was used to study fracture surface of the joints. The self-healing adhesives exhibit recovery of both cohesion and adhesion properties with room temperature healing.

Development of self-healing polymers via amine–epoxy chemistry: II. Systematic evaluation of self-healing performance

International Nuclear Information System (INIS)

Zhang, He; Yang, Jinglei

2014-01-01

Part I of this study (H Zhang and J Yang 2014 Smart Mater. Struct. 23 065003) reported the preparation and characterization of epoxy microcapsules (EP-capsules) and amine loaded hollow glass bubbles (AM-HGBs), and the modeling of a two-part self-healing system. In part II, the self-healing performance of this material system is systematically investigated. Various factors including the ratio, the total concentration and the size of the two carriers are studied as well as the healing temperature and the post heat treatment process. The best healing performance is obtained at a ratio of 1:3 of EP-capsules to AM-HGBs. It is observed that a higher concentration of larger carriers, together with a higher healing temperature, enables better healing behavior. Healing efficiency of up to 93% is obtained in these systems. In addition, post heat treatment decreases the healing efficiency due to stoichiometric mismatch of healing agents caused by leakage of amine in the HGBs at elevated temperature. (paper)

Development of self-healing polymers via amine-epoxy chemistry: II. Systematic evaluation of self-healing performance

Science.gov (United States)

Zhang, He; Yang, Jinglei

2014-06-01

Part I of this study (H Zhang and J Yang 2014 Smart Mater. Struct. 23 065003) reported the preparation and characterization of epoxy microcapsules (EP-capsules) and amine loaded hollow glass bubbles (AM-HGBs), and the modeling of a two-part self-healing system. In part II, the self-healing performance of this material system is systematically investigated. Various factors including the ratio, the total concentration and the size of the two carriers are studied as well as the healing temperature and the post heat treatment process. The best healing performance is obtained at a ratio of 1:3 of EP-capsules to AM-HGBs. It is observed that a higher concentration of larger carriers, together with a higher healing temperature, enables better healing behavior. Healing efficiency of up to 93% is obtained in these systems. In addition, post heat treatment decreases the healing efficiency due to stoichiometric mismatch of healing agents caused by leakage of amine in the HGBs at elevated temperature.

Interfacial self-healing of nanocomposite hydrogels: Theory and experiment

Science.gov (United States)

Wang, Qiming; Gao, Zheming; Yu, Kunhao

2017-12-01

Polymers with dynamic bonds are able to self-heal their fractured interfaces and restore the mechanical strengths. It is largely elusive how to analytically model this self-healing behavior to construct the mechanistic relationship between the self-healing properties (e.g., healed interfacial strength and equilibrium healing time) and the material compositions and healing conditions. Here, we take a self-healable nanocomposite hydrogel as an example to illustrate an interfacial self-healing theory for hydrogels with dynamic bonds. In the theory, we consider the free polymer chains diffuse across the interface and reform crosslinks to bridge the interface. We analytically reveal that the healed strengths of nanocomposite hydrogels increase with the healing time in an error-function-like form. The equilibrium self-healing time of the full-strength recovery decreases with the temperature and increases with the nanoparticle concentration. We further analytically reveal that the healed interfacial strength decreases with increasing delaying time before the healing process. The theoretical results quantitatively match with our experiments on nanosilica hydrogels, and also agree well with other researchers' experiments on nanoclay hydrogels. We expect that this theory would open promising avenues for quantitative understanding of the self-healing mechanics of various polymers with dynamic bonds, and offer insights for designing high-performance self-healing polymers.

A novel methodology for self-healing at the nanoscale in CNT/epoxy composites

Science.gov (United States)

Quigley, E.; Datta, S.; Chattopadhyay, A.

2016-04-01

Self-healing materials have the potential to repair induced damage and extend the service life of aerospace or civil components as well as prevent catastrophic failure. A novel technique to provide self-healing capabilities at the nanoscale in carbon nanotube/epoxy nanocomposites is presented in this paper. Carbon nanotubes (CNTs) functionalized with the healing agent (dicyclopentadiene) were used to fabricate self-healing CNT/epoxy nanocomposite films. The structure of CNTs was considered suitable for this application since they are nanosized, hollow, and provide a more consistent size distribution than polymeric nanocapsules. Specimens with different weight fractions of the functionalized CNTs were fabricated to explore the effect of weight fraction of functionalized CNTs on the extent of healing. Optical micrographs with different fluorescent filters showed partial or complete healing of damage approximately two to three weeks after damage was induced. Results indicate that by using CNTs to encapsulate a healing agent, crack growth in self-healing CNT/epoxy nanocomposites can be retarded, leading to safer materials that can autonomously repair itself.

Self-Healing Nanocomposites for Reusable Composite Cryotanks

Science.gov (United States)

Eberly, Daniel; Ou, Runqing; Karcz, Adam; Skandan, Ganesh

2013-01-01

nanoparticle additives. Unique nanoparticles were used that have been surface-functionalized to be compatible with the resin. Both organic and inorganic components toughen the matrix and result in a more impact-resistant COPV. In one resin system containing an inorganic nanomaterial additive, a significant improvement in burst performance was observed after the COPV was cryo-impact-damaged and then self-healed, with a greater than 10% improvement in burst pressure after the self-healing process was performed. Initial cross-sectional analysis via microscopy showed good resin infiltration of the carbon fibers and without voids. To further enhance the capability between the nanomaterial additives and the resin, a surface modification was successfully performed. A second specialty epoxy resin was prepared using a surface modified nanomaterial additive, and COPVs were fabricated. Steps were taken to improve the mechanical properties of the COPVs by using a low-viscosity resin system that contained a different curing agent. This lower viscosity improves the processing of the COPV, and preliminary results show that the burst pressure of these new vessels is 20 to 25% higher than that of the original. The self-healing concept demonstrated in this research and development effort represents a platform technology, and the self-healing property is neither restricted to the particular epoxy system used here, nor to the COPV application. Self-healing is a direct result of a unique phase separated morphology created via the resin and is aided by the nanoparticles. The self-healing function can be introduced to other customer-specific resin systems in coating, bulk, or composite applications provided that the unique phase separated morphology can be enabled in those systems.

Self-healing in single and multiple fiber(s reinforced polymer composites

Directory of Open Access Journals (Sweden)

Woldesenbet E.

2010-06-01

Full Text Available You Polymer composites have been attractive medium to introduce the autonomic healing concept into modern day engineering materials. To date, there has been significant research in self-healing polymeric materials including several studies specifically in fiber reinforced polymers. Even though several methods have been suggested in autonomic healing materials, the concept of repair by bleeding of enclosed functional agents has garnered wide attention by the scientific community. A self-healing fiber reinforced polymer composite has been developed. Tensile tests are carried out on specimens that are fabricated by using the following components: hollow and solid glass fibers, healing agent, catalysts, multi-walled carbon nanotubes, and a polymer resin matrix. The test results have demonstrated that single fiber polymer composites and multiple fiber reinforced polymer matrix composites with healing agents and catalysts have provided 90.7% and 76.55% restoration of the original tensile strength, respectively. Incorporation of functionalized multi-walled carbon nanotubes in the healing medium of the single fiber polymer composite has provided additional efficiency. Healing is found to be localized, allowing multiple healing in the presence of several cracks.

Autonomous self-healing structural composites with bio-inspired design.

Science.gov (United States)

D'Elia, Eleonora; Eslava, Salvador; Miranda, Miriam; Georgiou, Theoni K; Saiz, Eduardo

2016-05-05

Strong and tough natural composites such as bone, silk or nacre are often built from stiff blocks bound together using thin interfacial soft layers that can also provide sacrificial bonds for self-repair. Here we show that it is possible exploit this design in order to create self-healing structural composites by using thin supramolecular polymer interfaces between ceramic blocks. We have built model brick-and-mortar structures with ceramic contents above 95 vol% that exhibit strengths of the order of MPa (three orders of magnitude higher than the interfacial polymer) and fracture energies that are two orders of magnitude higher than those of the glass bricks. More importantly, these properties can be fully recovered after fracture without using external stimuli or delivering healing agents. This approach demonstrates a very promising route towards the design of strong, ideal self-healing materials able to self-repair repeatedly without degradation or external stimuli.

Abalone water-soluble matrix for self-healing biomineralization of tooth defects

Energy Technology Data Exchange (ETDEWEB)

Wen, Zhenliang [Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou 350002 (China); Chen, Jingdi, E-mail: ibptcjd@fzu.edu.cn [Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou 350002 (China); Wang, Hailiang [The Affiliated Stomatological Hospital, Fujian Medical University, Fuzhou 350002 (China); Zhong, Shengnan; Hu, Yimin; Wang, Zhili [Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou 350002 (China); Zhang, Qiqing, E-mail: zhangqiq@126.com [Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou 350002 (China); Institute of Biomedical Engineering, Chinese Academy of Medical Science & Peking Union Medical College, Tianjin 300192 (China)

2016-10-01

Enamel cannot heal by itself if damaged. Hydroxyapatite (HAP) is main component of human enamel. Formation of enamel-like materials for healing enamel defects remains a challenge. In this paper, we successfully isolated the abalone water-soluble matrix (AWSM) with 1.53 wt% the abalone water-soluble protein (AWSPro) and 2.04 wt% the abalone water-soluble polysaccharide (AWSPs) from abandoned abalone shell, and self-healing biomineralization of tooth defects was successfully achieved in vitro. Based on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), hot field emission scanning electron microscopy (HFESEM) and energy dispersive spectrometer (EDS) analysis, the results showed that the AWSM can efficiently induce remineralization of HAP. The enamel-like HAP was successfully achieved onto etched enamel's surface due to the presence of the AWSM. Moreover, the remineralized effect of eroded enamel was growing with the increase of the AWSM. This study provides a solution to the resource waste and environmental pollution caused by abandoned abalone shell, and we provides a new method for self-healing remineralization of enamel defects by AWSM and develops a novel dental material for potential clinical dentistry application. - Graphical abstract: In this paper, we successfully isolated the abalone water-soluble matrix (AWSM) with 1.53 wt% abalone water-soluble protein (AWSPro) and 2.04 wt% abalone water-soluble polysaccharide (AWSPs) from abandoned abalone shell, and self-healing biomineralization of tooth defects was successfully achieved in vitro by self-organized. Display Omitted - Highlights: • Provides a solution to the resource waste and environmental pollution caused by abandoned abalone shell. • The abalone shell water-soluble matrix contains protein and polysaccharide. • The abalone water-soluble matrix can efficiently induce remineralization of HAP by self-organized. • Achieved self-healing biomineralization of tooth defects in

Abalone water-soluble matrix for self-healing biomineralization of tooth defects

International Nuclear Information System (INIS)

Wen, Zhenliang; Chen, Jingdi; Wang, Hailiang; Zhong, Shengnan; Hu, Yimin; Wang, Zhili; Zhang, Qiqing

2016-01-01

Enamel cannot heal by itself if damaged. Hydroxyapatite (HAP) is main component of human enamel. Formation of enamel-like materials for healing enamel defects remains a challenge. In this paper, we successfully isolated the abalone water-soluble matrix (AWSM) with 1.53 wt% the abalone water-soluble protein (AWSPro) and 2.04 wt% the abalone water-soluble polysaccharide (AWSPs) from abandoned abalone shell, and self-healing biomineralization of tooth defects was successfully achieved in vitro. Based on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), hot field emission scanning electron microscopy (HFESEM) and energy dispersive spectrometer (EDS) analysis, the results showed that the AWSM can efficiently induce remineralization of HAP. The enamel-like HAP was successfully achieved onto etched enamel's surface due to the presence of the AWSM. Moreover, the remineralized effect of eroded enamel was growing with the increase of the AWSM. This study provides a solution to the resource waste and environmental pollution caused by abandoned abalone shell, and we provides a new method for self-healing remineralization of enamel defects by AWSM and develops a novel dental material for potential clinical dentistry application. - Graphical abstract: In this paper, we successfully isolated the abalone water-soluble matrix (AWSM) with 1.53 wt% abalone water-soluble protein (AWSPro) and 2.04 wt% abalone water-soluble polysaccharide (AWSPs) from abandoned abalone shell, and self-healing biomineralization of tooth defects was successfully achieved in vitro by self-organized. Display Omitted - Highlights: • Provides a solution to the resource waste and environmental pollution caused by abandoned abalone shell. • The abalone shell water-soluble matrix contains protein and polysaccharide. • The abalone water-soluble matrix can efficiently induce remineralization of HAP by self-organized. • Achieved self-healing biomineralization of tooth defects in vitro.

Self-healing concrete by use of microencapsulated bacterial spores

International Nuclear Information System (INIS)

Wang, J.Y.; Soens, H.; Verstraete, W.; De Belie, N.

2014-01-01

Microcapsules were applied to encapsulate bacterial spores for self-healing concrete. The viability of encapsulated spores and the influence of microcapsules on mortar specimens were investigated first. Breakage of the microcapsules upon cracking was verified by Scanning Electron Microscopy. Self-healing capacity was evaluated by crack healing ratio and the water permeability. The results indicated that the healing ratio in the specimens with bio-microcapsules was higher (48%–80%) than in those without bacteria (18%–50%). The maximum crack width healed in the specimens of the bacteria series was 970 μm, about 4 times that of the non-bacteria series (max 250 μm). The overall water permeability in the bacteria series was about 10 times lower than that in non-bacteria series. Wet–dry cycles were found to stimulate self-healing in mortar specimens with encapsulated bacteria. No self-healing was observed in all specimens stored at 95%RH, indicating that the presence of liquid water is an essential component for self-healing

Self-healing concrete by use of microencapsulated bacterial spores

Energy Technology Data Exchange (ETDEWEB)

Wang, J.Y. [Magnel Laboratory for Concrete Research, Faculty of Engineering and Architecture, Ghent University, TechnologieparkZwijnaarde 904, B-9052 Ghent (Belgium); Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Soens, H. [Devan Chemicals NV, Klein Frankrijk 18, 9600 Ronse (Belgium); Verstraete, W. [Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); De Belie, N., E-mail: nele.debelie@ugent.be [Magnel Laboratory for Concrete Research, Faculty of Engineering and Architecture, Ghent University, TechnologieparkZwijnaarde 904, B-9052 Ghent (Belgium)

2014-02-15

Microcapsules were applied to encapsulate bacterial spores for self-healing concrete. The viability of encapsulated spores and the influence of microcapsules on mortar specimens were investigated first. Breakage of the microcapsules upon cracking was verified by Scanning Electron Microscopy. Self-healing capacity was evaluated by crack healing ratio and the water permeability. The results indicated that the healing ratio in the specimens with bio-microcapsules was higher (48%–80%) than in those without bacteria (18%–50%). The maximum crack width healed in the specimens of the bacteria series was 970 μm, about 4 times that of the non-bacteria series (max 250 μm). The overall water permeability in the bacteria series was about 10 times lower than that in non-bacteria series. Wet–dry cycles were found to stimulate self-healing in mortar specimens with encapsulated bacteria. No self-healing was observed in all specimens stored at 95%RH, indicating that the presence of liquid water is an essential component for self-healing.

Self-Healing and Damage Resilience for Soft Robotics: A Review

Directory of Open Access Journals (Sweden)

R. Adam Bilodeau

2017-10-01

Full Text Available Advances in soft robotics will be crucial to the next generation of robot–human interfaces. Soft material systems embed safety at the material level, providing additional safeguards that will expedite their placement alongside humans and other biological systems. However, in order to function in unpredictable, uncontrolled environments alongside biological systems, soft robotic systems should be as robust in their ability to recover from damage as their biological counterparts. There exists a great deal of work on self-healing materials, particularly polymeric and elastomeric materials that can self-heal through a wide variety of tools and techniques. Fortunately, most emerging soft robotic systems are constructed from polymeric or elastomeric materials, so this work can be of immediate benefit to the soft robotics community. Though the field of soft robotics is still nascent as a whole, self-healing and damage resilient systems are beginning to be incorporated into three key support pillars that are enabling the future of soft robotics: actuators, structures, and sensors. This article reviews the state-of-the-art in damage resilience and self-healing materials and devices as applied to these three pillars. This review also discusses future applications for soft robots that incorporate self-healing capabilities.

Self-healing polymers

Science.gov (United States)

Klein, Daniel J. (Inventor)

2011-01-01

A three dimensional structure fabricated from a self-healing polymeric material, comprising poly(ester amides) obtained from ethylene glycol, azelaic acid and 1,1-aminoundecanoic acid, wherein polymeric material has a melt index above 2.5 g/10 min. as determined by ASTM D1238 at 190.degree. C. and 2.16kg, impact resistance and ductility sufficient to resist cracking and brittle fracture upon impact by a 9 mm bullet fired at a temperature of about 29.degree. C. at subsonic speed in a range from about 800 feet/sec to about 1000 feet/sec. It has been determined that the important factors necessary for self-healing behavior of polymers include sufficient impact strength, control of the degree of crystallinity, low melting point and the ability to instantly melt at impacted area.

THE USE OF A CODED HEALING ABUTMENT AS AN IMPRESSION COPING TO DESIGN AND MILL AN INDIVIDUALIZED ANATOMIC ABUTMENT : A CLINICAL REPORT

NARCIS (Netherlands)

Telleman, Gerdien; Raghoebar, Gerry M.; Vissink, Arjan; Meijer, Henny J. A.

A coded implant healing abutment makes an impression at the implant level no longer necessary. An impression is made of the healing abutment, which is placed onto the implant directly after implant placement. The codes embedded in the occlusal surface of the healing abutment provide essential

Proteinaceous Resin and Hydrophilic Encapsulation: A Self-Healing-Related Study

Science.gov (United States)

Zheng, Ting

Inspired by living organisms, self-healing materials have been designed as smart materials. Their automatic healing nature is achieved through the use of capsule in which the healing agent is encapsulated. The occurrence of cracks leads to ripping of the capsule, along with crack propagation and release of the healing agent that wets the crack surface to eventually heal (bond) the crack. Such automatic repair of the crack significantly extends the service life of the material. A vast majority of existing self-healing systems have been designed for the epoxy matrix - the most common commercially used thermoset - that possesses low crack resistance. Currently, self-healing systems have not yet been introduced for fully protein-based materials, despite their great potential to replace currently used synthesis precursors for the latter and the eco-friendly nature of self-healing materials. This has been probably due to two major obstacles: poor mechanical properties of the protein-based matrix, and extreme difficulty associated with the encapsulation of hydrophilic healing agents suitable for the protein-based matrix. This study provides possible solutions towards addressing both these obstacles. To improve the inherent mechanical properties of protein-based resin, soy protein isolate (SPI) was chosen as the model in this study. Dialdehyde carboxymethyl cellulose (DCMC) was synthesized and used as the crosslinking agent to modify the SPI film. As-synthesized DCMC - a fully bio-based material - exhibited high mechanical strength, excellent thermal stability, and reduced moisture sensitivity. Good compatibility and effective crosslinking were believed to be the key reasons for such property enhancements. However, these were accompanied by poor crack resistance, where self-healing is a pertinent solution. A novel healing system for the protein matrix was designed in this work via the use of formaldehyde as a healing agent. Subsequently, the well-acknowledged challenge, e

Self-Healing Networks: Redundancy and Structure

Science.gov (United States)

Quattrociocchi, Walter; Caldarelli, Guido; Scala, Antonio

2014-01-01

We introduce the concept of self-healing in the field of complex networks modelling; in particular, self-healing capabilities are implemented through distributed communication protocols that exploit redundant links to recover the connectivity of the system. We then analyze the effect of the level of redundancy on the resilience to multiple failures; in particular, we measure the fraction of nodes still served for increasing levels of network damages. Finally, we study the effects of redundancy under different connectivity patterns—from planar grids, to small-world, up to scale-free networks—on healing performances. Small-world topologies show that introducing some long-range connections in planar grids greatly enhances the resilience to multiple failures with performances comparable to the case of the most resilient (and least realistic) scale-free structures. Obvious applications of self-healing are in the important field of infrastructural networks like gas, power, water, oil distribution systems. PMID:24533065

Self-healing composites: in-situ repair solutions

NARCIS (Netherlands)

Coope, T.S.; Luterbacher, R.; Turkenburg, D.H.; Fischer, H.R.; Bond, I.P.

2015-01-01

Realising self-healing composites in a commercial environment remains a challenge for the transport sector. Herein, this research considers the design envelope and the implications of embedding self-healing agents into commercially relevant fibre reinforced polymer (FRP) composite applications. A

An overview on the research on self-healing concrete at Politecnico di Milano

Directory of Open Access Journals (Sweden)

Ferrara Liberato

2017-01-01

Full Text Available Self-healing cement based materials, by controlling and repairing cracks, could prevent “permeation of driving factors for deterioration”, thus extending the structure service life, and even provide partial recovery of engineering properties relevant to the application. The author’s group has undertaken a comprehensive investigation focusing on both experimental characterization and numerical modelling of the self-healing capacity of a broad category of cementitious composites, including high performance cementitious composites reinforced with different kinds of fibres. Both autogenous healing has been considered and self-healing engineered techniques, including the use of pre-saturated natural fibres and of crystalline admixtures. Tailored methodologies have been employed to characterize the healing capacity under different exposure conditions and for different time spans, ranging up to two years. The healing capacity has been quantified by means of suitably defined “healing indices”, based on the recovery of mechanical properties correlated to the amount of crack closure, measured by means of optical microscopy. A predictive modelling approach, based on modified micro-plane model, has been formulated. The whole investigation represents a step towards the reliable and consistent incorporation of self-healing concepts and effects into a durability-based design framework for engineering applications made of or retrofitted with self- healing concrete and cementitious composites.

Active self-healing encapsulation of vaccine antigens in PLGA microspheres

Science.gov (United States)

Desai, Kashappa-Goud H.; Schwendeman, Steven P.

2013-01-01

Herein, we describe the detailed development of a simple and effective method to microencapsulate vaccine antigens in poly(lactic-co-glycolic acid) (PLGA) by simple mixing of preformed active self-microencapsulating (SM) PLGA microspheres in a low concentration aqueous antigen solution at modest temperature (10-38 °C). Co-encapsulating protein-sorbing vaccine adjuvants and polymer plasticizers were used to “actively” load the protein in the polymer pores and facilitate polymer self-healing at temperature > hydrated polymer glass transition temperature, respectively. The microsphere formulation parameters and loading conditions to provide optimal active self-healing microencapsulation of vaccine antigen in PLGA was investigated. Active self-healing encapsulation of two vaccine antigens, ovalbumin and tetanus toxoid (TT), in PLGA microspheres was adjusted by preparing blank microspheres containing different vaccine adjuvant (aluminum hydroxide (Al(OH)3) or calcium phosphate). Active loading of vaccine antigen in Al(OH)3-PLGA microspheres was found to: a) increase proportionally with an increasing loading of Al(OH)3 (0.88-3 wt%) and addition of porosigen, b) decrease when the inner Al(OH)3/trehalose phase to 1 mL outer oil phase and size of microspheres was respectively > 0.2 mL and 63 μm, and c) change negligibly by PLGA concentration and initial incubation (loading) temperature. Encapsulation of protein sorbing Al(OH)3 in PLGA microspheres resulted in suppression of self-healing of PLGA pores, which was then overcome by improving polymer chain mobility, which in turn was accomplished by coincorporating hydrophobic plasticizers in PLGA. Active self-healing microencapsulation of manufacturing process-labile TT in PLGA was found to: a) obviate micronization- and organic solvent-induced TT degradation, b) improve antigen loading (1.4-1.8 wt% TT) and encapsulation efficiency (~ 97%), c) provide nearly homogeneous distribution and stabilization of antigen in polymer

Self-Healing Capability of Fiber-Reinforced Cementitious Composites for Recovery of Watertightness and Mechanical Properties

Directory of Open Access Journals (Sweden)

Tomoya Nishiwaki

2014-03-01

Full Text Available Various types of fiber reinforced cementitious composites (FRCCs were experimentally studied to evaluate their self-healing capabilities regarding their watertightness and mechanical properties. Cracks were induced in the FRCC specimens during a tensile loading test, and the specimens were then immersed in static water for self-healing. By water permeability and reloading tests, it was determined that the FRCCs containing synthetic fiber and cracks of width within a certain range (<0.1 mm exhibited good self-healing capabilities regarding their watertightness. Particularly, the high polarity of the synthetic fiber (polyvinyl alcohol (PVA series and hybrid fiber reinforcing (polyethylene (PE and steel code (SC series showed high recovery ratio. Moreover, these series also showed high potential of self-healing of mechanical properties. It was confirmed that recovery of mechanical property could be obtained only in case when crack width was sufficiently narrow, both the visible surface cracks and the very fine cracks around the bridging of the SC fibers. Recovery of the bond strength by filling of the very fine cracks around the bridging fibers enhanced the recovery of the mechanical property.

Healing agent for self-healing cementious material

NARCIS (Netherlands)

Jonkers, H.M.

2011-01-01

The invention provides a process for the production of a cementious material. The process comprises mixing cement starting materials and a particulate healing agent to provide the cementious material. The healing agent comprises coated particles, wherein the coated particles comprise bacterial

Layer-by-Layer Assembly of a Self-Healing Anticorrosion Coating on Magnesium Alloys.

Science.gov (United States)

Fan, Fan; Zhou, Chunyu; Wang, Xu; Szpunar, Jerzy

2015-12-16

Fabrication of self-healing anticorrosion coatings has attracted attention as it has the ability to extend the service life and prevent the substrate from corrosive attack. However, a coating system with a rapid self-healing ability and an improved corrosion resistance is rarely reported. In this work, we developed a self-healing anticorrosion coating on a magnesium alloy (AZ31). The coating comprises a cerium-based conversion layer, a graphene oxide layer, and a branched poly(ethylene imine) (PEI)/poly(acrylic acid) (PAA) multilayer. We incorporated the graphene oxide as corrosion inhibitors and used the PEI/PAA multilayers to provide the self-healing ability to the coating systems. X-ray diffraction (XRD) and Raman spectroscopy were used to characterize the composition of the multilayers, and scanning electron microscopy (SEM) was used to analyze the surface morphology. The electrochemical impedance spectroscopy (EIS) results illustrate the improved corrosion resistance of the coating. The proposed coating also has a rapid self-healing ability in the presence of water.

Developing Flexible, High Performance Polymers with Self-Healing Capabilities

Science.gov (United States)

Jolley, Scott T.; Williams, Martha K.; Gibson, Tracy L.; Caraccio, Anne J.

2011-01-01

Flexible, high performance polymers such as polyimides are often employed in aerospace applications. They typically find uses in areas where improved physical characteristics such as fire resistance, long term thermal stability, and solvent resistance are required. It is anticipated that such polymers could find uses in future long duration exploration missions as well. Their use would be even more advantageous if self-healing capability or mechanisms could be incorporated into these polymers. Such innovative approaches are currently being studied at the NASA Kennedy Space Center for use in high performance wiring systems or inflatable and habitation structures. Self-healing or self-sealing capability would significantly reduce maintenance requirements, and increase the safety and reliability performance of the systems into which these polymers would be incorporated. Many unique challenges need to be overcome in order to incorporate a self-healing mechanism into flexible, high performance polymers. Significant research into the incorporation of a self-healing mechanism into structural composites has been carried out over the past decade by a number of groups, notable among them being the University of I1linois [I]. Various mechanisms for the introduction of self-healing have been investigated. Examples of these are: 1) Microcapsule-based healant delivery. 2) Vascular network delivery. 3) Damage induced triggering of latent substrate properties. Successful self-healing has been demonstrated in structural epoxy systems with almost complete reestablishment of composite strength being achieved through the use of microcapsulation technology. However, the incorporation of a self-healing mechanism into a system in which the material is flexible, or a thin film, is much more challenging. In the case of using microencapsulation, healant core content must be small enough to reside in films less than 0.1 millimeters thick, and must overcome significant capillary and surface

‘Containers’ for self-healing epoxy composites and coating: Trends and advances

Directory of Open Access Journals (Sweden)

P. Vijayan

2016-06-01

Full Text Available The introduction of self-healing functionality into epoxy matrix is an important and challenging topic. Various micro/nano containers loaded self-healing agents are developed and incorporated into epoxy matrix to impart self-healing ability. The current report reviews the major findings in the area of self-healing epoxy composites and coatings with special emphasis on these containers. The preparation and use of polymer micro/nano capsules, polymer fibers, hollow glass fibers/bubbles, inorganic nanotubes, inorganic meso- and nano-porous materials, carbon nanotubes etc. as self-healing containers are outlined. The nature of the container and its response to the external stimulations greatly influence the self-healing performance. The self-healing mechanism associated with each type of container and the role of container parameters on self-healing performance of self-healing epoxy systems are reviewed. Comparison of the efficiency offered by different types of containers is introduced. Finally, the selection of containers to develop cost effective and green self-healing systems are mentioned.

A review: Self-healing in cementitious materials and engineered cementitious composite as a self-healing material

DEFF Research Database (Denmark)

Wu, Min; Johannesson, Björn; Geiker, Mette

2012-01-01

.e. the use of hollow fibers, microencapsulation, expansive agents and mineral admixtures, bacteria and shape memory materials, are reviewed and summarized. A comparison study is conducted subsequently on different strategies to self-healing and on different healing agents used as well. Engineered...

eDNA: A Bio-Inspired Reconfigurable Hardware Cell Architecture Supporting Self-organisation and Self-healing

DEFF Research Database (Denmark)

Boesen, Michael Reibel; Madsen, Jan

2009-01-01

This paper presents the concept of a biological inspired reconfigurable hardware cell architecture which supports self-organisation and self-healing. Two fundamental processes in biology, namely fertilization-to-birth and cell self-healing have inspired the development of this cell architecture...... to simulate our self-organisation and self-healing algorithms and the results obtained from this looks promising....

Development of Composites with a Self-Healing Function

Directory of Open Access Journals (Sweden)

Andrey ANISKEVICH

2015-03-01

Full Text Available This research aimed to realize experimentally the facilevascular self-healing system in epoxy glass fibre reinforced composite. Using flexiblepolytetrafluoroethylene tubes as removable preforms, the channels were embeddedinto both neat epoxy resin and unidirectional glass-fibre reinforced epoxy laminate.Room temperature curable epoxy resin with a surfactant and an amine-basedhardener were the components of the binary healing agent. The specimens oftapered double cantilever beam geometry were subjected to Mode I fracture tests.Fracture of specimens released the healing agent from channels and triggeredself-healing process of the crack. Tested neat epoxy resin specimensdemonstrated recovery of fracture toughness ca. 70 % after 24 h of self-healingat 50°C. Unidirectional laminate specimens (250×23×1.2 mm were made by vacuuminfusion method from two layers of glass yarns with 5 embedded channels aligningto reinforcing fibers. The channels were alternately filled with components of thehealing agent and then sealed. It was revealed that the embedded vascularchannels in specimens had very little effect on their elastic modulus. Theexperimental program included multiple three-point bending tests of specimensfor their initial damage and self-healing of specimens during their heat treatmentand following exposure at room temperature. Static and dynamic flexural moduli ofelasticity were determined by three-point bending and cantilever beam vibrationat all stages of the test program. The healing efficiency was evaluated as a relativechange of elastic modulus. The efficiency ca. 30 % was reached during 24 h at50°C and additionally increased up ca. 40 % after more than 3 weeks of roomtemperature exposure. The sealed healing agent was capable of maintaining thecapacity for self-healing for at least six months. The research resultsdemonstrated capacity of the macro-channel approach for self-healing realizationin multifunctional polymer composite materials

Self-healing of lime based mortars: Microscopy observations on case studies

NARCIS (Netherlands)

Lubelli, B.; Nijland, T.G.; Hees, R.P.J. van

2011-01-01

Lime mortars have, up to a certain extent, a self-healing capacity which may contribute to their durability. Self-healing in lime mortars consists of a process of dissolution, transport and re-precipitation of calcium compounds to heal cracks and fissures. The spontaneous occurrence of self-healing

Self-healing of lime based mortars : Microscopy observations on case studies

NARCIS (Netherlands)

Lubelli, B.; Nijland, T.G.; Van Hees, R.P.J.

2011-01-01

Lime mortars have, up to a certain extent, a self-healing capacity which may contribute to their durability. Self-healing in lime mortars consists of a process of dissolution, transport and re-precipitation of calcium compounds to heal cracks and fissures. The spontaneous occurrence of self-healing

Light triggered interfacial damage self-healing of poly(p-phenylene benzobisoxazole) fiber composites

Science.gov (United States)

Hu, Zhen; Shao, Qing; Huang, Yudong; Yu, Long; Zhang, Dayu; Xu, Xirong; Lin, Jing; Liu, Hu; Guo, Zhanhu

2018-05-01

The interfacial microcracks in the resin matrix composites are difficult to be detected and repaired. However, the self-healing concept provides opportunities to fabricate composites with unusual properties. In the present study, photothermal conversion Ag-Cu2S nanoparticles were immobilized onto poly(p-phenylene benzobisoxazole) (PBO) fibers via a polydopamine chemistry. Benefitting from the photothermal effects of Ag-Cu2S, the obtained PBO fibers (Ag-Cu2S-PBO) efficiently converted the light energy into heat under Xenon lamp irradiation. Then, single PBO fiber composites were prepared using thermoplastic polyurethane as the matrix. It was found that the interfacial damage caused by single fiber pull-out was simply self-healed by Xe light irradiation. This wonderful interfacial damage self-healing property was mainly attributed to the in situ heating generation via photothermal effects of Ag-Cu2S in the composite interface. This paper reports a novel strategy to construct advanced composites with light-triggered self-healing properties, which will provide inspiration for preparing high performance composite materials.

Micromechanical properties of a new polymeric microcapsule for self-healing cementitious materials

NARCIS (Netherlands)

Lv, Leyang; Schlangen, H.E.J.G.; Yang, Z.; Xing, Feng

2016-01-01

Self-healing cementitious materials containing a microencapsulated healing agent are appealing due to their great application potential in improving the serviceability and durability of concrete structures. In this study, poly(phenol-formaldehyde) (PF) microcapsules that aim to provide a

Self-healing phenomena in cement-based materials state-of-the-art report of RILEM Technical Committee 221-SHC Self-Healing Phenomena in Cement-Based Materials

CERN Document Server

Tittelboom, Kim; Belie, Nele; Schlangen, Erik

2013-01-01

Self-healing materials are man-made materials which have the built-in capability to repair damage. Failure in materials is often caused by the occurrence of small microcracks throughout the material. In self-healing materials phenomena are triggered to counteract these microcracks. These processes are ideally triggered by the occurrence of damage itself. Thus far, the self-healing capacity of cement-based materials has been considered as something "extra". This could be called passive self-healing, since it was not a designed feature of the material, but an inherent property of it. Centuries-old buildings have been said to have survived these centuries because of the inherent self-healing capacity of the binders used for cementing building blocks together. In this State-of-the-Art Report a closer look is taken at self-healing phenomena in cement-based materials. It is shown what options are available to design for this effect rather than have it occur as a "coincidental extra".

A probabilistic method for determining the volume fraction of pre-embedded capsules in self-healing materials

International Nuclear Information System (INIS)

Lv, Zhong; Chen, Huisu

2014-01-01

Autonomous healing of cracks using pre-embedded capsules containing healing agent is becoming a promising approach to restore the strength of damaged structures. In addition to the material properties, the size and volume fraction of capsules influence crack healing in the matrix. Understanding the crack and capsule interaction is critical in the development and design of structures made of self-healing materials. Assuming that the pre-embedded capsules are randomly dispersed we theoretically model flat ellipsoidal crack interaction with capsules and determine the probability of a crack intersecting the pre-embedded capsules i.e. the self-healing probability. We also develop a probabilistic model of a crack simultaneously meeting with capsules and catalyst carriers in two-component self-healing system matrix. Using a risk-based healing approach, we determine the volume fraction and size of the pre-embedded capsules that are required to achieve a certain self-healing probability. To understand the effect of the shape of the capsules on self-healing we theoretically modeled crack interaction with spherical and cylindrical capsules. We compared the results of our theoretical model with Monte-Carlo simulations of crack interaction with capsules. The formulae presented in this paper will provide guidelines for engineers working with self-healing structures in material selection and sustenance. (paper)

Self-Healing Textile: Enzyme Encapsulated Layer-by-Layer Structural Proteins.

Science.gov (United States)

Gaddes, David; Jung, Huihun; Pena-Francesch, Abdon; Dion, Genevieve; Tadigadapa, Srinivas; Dressick, Walter J; Demirel, Melik C

2016-08-10

Self-healing materials, which enable an autonomous repair response to damage, are highly desirable for the long-term reliability of woven or nonwoven textiles. Polyelectrolyte layer-by-layer (LbL) films are of considerable interest as self-healing coatings due to the mobility of the components comprising the film. In this work mechanically stable self-healing films were fabricated through construction of a polyelectrolyte LbL film containing squid ring teeth (SRT) proteins. SRTs are structural proteins with unique self-healing properties and high elastic modulus in both dry and wet conditions (>2 GPa) due to their semicrystalline architecture. We demonstrate LbL construction of multilayers containing native and recombinant SRT proteins capable of self-healing defects. Additionally, we show these films are capable of utilizing functional biomolecules by incorporating an enzyme into the SRT multilayer. Urease was chosen as a model enzyme of interest to test its activity via fluorescence assay. Successful construction of the SRT films demonstrates the use of mechanically stable self-healing coatings, which can incorporate biomolecules for more complex protective functionalities for advanced functional fabrics.

Wire Insulation Incorporating Self-Healing Polymers (WIISP), Phase II

Data.gov (United States)

National Aeronautics and Space Administration — NextGen and Virginia Tech are developing a self-healing material for wire insulation using a class of ionomeric polymers. These ionomers exhibit self-healing...

Possibility of self-healing by using capsules and vascular system to provide water in cementitious materials

NARCIS (Netherlands)

Huang, H.; Ye, G.

2013-01-01

Since self-healing of cracks is able to improve the durability of concrete structures, it has attracted much attention in the recent years. As known, in concrete matrix there are large amounts of cement grains remaining unhydrated, particularly in high performance concrete. Further hydration of

Self-healing of Bessel-like beams with longitudinally dependent cone angles

CSIR Research Space (South Africa)

Litvin, I

2015-09-01

Full Text Available non-diffracting propagation region. Here we show that such beams can self-heal. Moreover, in contrast to Bessel beams where the self-healing distance is constant, here the self-healing distance is dependent on where the obstruction is placed...

A highly stretchable autonomous self-healing elastomer

Science.gov (United States)

Li, Cheng-Hui; Wang, Chao; Keplinger, Christoph; Zuo, Jing-Lin; Jin, Lihua; Sun, Yang; Zheng, Peng; Cao, Yi; Lissel, Franziska; Linder, Christian; You, Xiao-Zeng; Bao, Zhenan

2016-06-01

It is a challenge to synthesize materials that possess the properties of biological muscles—strong, elastic and capable of self-healing. Herein we report a network of poly(dimethylsiloxane) polymer chains crosslinked by coordination complexes that combines high stretchability, high dielectric strength, autonomous self-healing and mechanical actuation. The healing process can take place at a temperature as low as -20 °C and is not significantly affected by surface ageing and moisture. The crosslinking complexes used consist of 2,6-pyridinedicarboxamide ligands that coordinate to Fe(III) centres through three different interactions: a strong pyridyl-iron one, and two weaker carboxamido-iron ones through both the nitrogen and oxygen atoms of the carboxamide groups. As a result, the iron-ligand bonds can readily break and re-form while the iron centres still remain attached to the ligands through the stronger interaction with the pyridyl ring, which enables reversible unfolding and refolding of the chains. We hypothesize that this behaviour supports the high stretchability and self-healing capability of the material.

A review on self-healing in reinforced concrete structures in view of serving conditions.

NARCIS (Netherlands)

Huang, H.; Ye, G.

2014-01-01

In this paper, different mechanisms of self-healing, i.e. self-healing based on adhesive agents, self-healing based on bacteria, self-healing based on autogenous self-healing were described. Their required conditions were summarized. The previous investigations showed that all mechanisms of

Micromechanical Properties of a New Polymeric Microcapsule for Self-Healing Cementitious Materials

Directory of Open Access Journals (Sweden)

Leyang Lv

2016-12-01

Full Text Available Self-healing cementitious materials containing a microencapsulated healing agent are appealing due to their great application potential in improving the serviceability and durability of concrete structures. In this study, poly(phenol–formaldehyde (PF microcapsules that aim to provide a self-healing function for cementitious materials were prepared by an in situ polymerization reaction. Size gradation of the synthesized microcapsules was achieved through a series of sieving processes. The shell thickness and the diameter of single microcapsules was accurately measured under environmental scanning electron microscopy (ESEM. The relationship between the physical properties of the synthesized microcapsules and their micromechanical properties were investigated using nanoindentation. The results of the mechanical tests show that, with the increase of the mean size of microcapsules and the decrease of shell thickness, the mechanical force required to trigger the self-healing function of microcapsules increased correspondingly from 68.5 ± 41.6 mN to 198.5 ± 31.6 mN, featuring a multi-sensitive trigger function. Finally, the rupture behavior and crack surface of cement paste with embedded microcapsules were observed and analyzed using X-ray computed tomography (XCT. The synthesized PF microcapsules may find potential application in self-healing cementitious materials.

Development of Micro and Nanostructured Materials for Interfacial Self-Healing

Science.gov (United States)

Blaiszik, Benjamin James

2009-01-01

Damage in polymeric coatings, adhesives, microelectronic components, and composites spans many length scales. For small scale damage, autonomic self-healing can repair multiple damage modes without manual intervention. In autonomic self-healing materials, a healing response is triggered by damage to the material. Size scale considerations, such as…

Congenital self-healing reticulohistiocytosis - an important diagnostic challenge

DEFF Research Database (Denmark)

Jensen, Marie Louise Slott; Bygum, Anette; Clemmensen, Ole

2011-01-01

Aim:  To present current and new knowledge on congenital self-healing reticulohistiocytosis, a benign variant of cutaneous Langerhans cell histiocytosis presenting with skin lesions in the neonatal period. Methods:  We describe and photo document two cases of this rare disease and review the lite......Aim:  To present current and new knowledge on congenital self-healing reticulohistiocytosis, a benign variant of cutaneous Langerhans cell histiocytosis presenting with skin lesions in the neonatal period. Methods:  We describe and photo document two cases of this rare disease and review...... the literature. Results:  Only few newborns have acute access to a neonatal dermatologist and we demonstrate how the spontaneous cutaneous involution may happen even prior to the first dermatological assessment. As no sole criterion can reliably distinguish the self-healing form from disseminated disease......, multidisciplinary assessment and follow up are essential. Conclusion:  Our data document how easily the diagnosis congenital self-healing reticulocytosis may be missed and emphasize the importance and value of instant clinical photographing at the neonatal unit and the use of teledermatology whenever congenital...

CuAAC-Based Click Chemistry in Self-Healing Polymers.

Science.gov (United States)

Döhler, Diana; Michael, Philipp; Binder, Wolfgang H

2017-10-17

Click chemistry has emerged as a significant tool for materials science, organic chemistry, and bioscience. Based on the initial concept of Barry Sharpless in 2001, the copper(I)-catalyzed azide/alkyne cycloaddition (CuAAC) reaction has triggered a plethora of chemical concepts for linking molecules and building blocks under ambient conditions, forming the basis for applications in autonomous cross-linking materials. Self-healing systems on the other hand are often based on mild cross-linking chemistries that are able to react either autonomously or upon an external trigger. In the ideal case, self-healing takes place efficiently at low temperatures, independent of the substrate(s) used, by forming strong and stable networks, binding to the newly generated (cracked) interfaces to restore the original material properties. The use of the CuAAC in self-healing systems, most of all the careful design of copper-based catalysts linked to additives as well as the chemical diversity of substrates, has led to an enormous potential of applications of this singular reaction. The implementation of click-based strategies in self-healing systems therefore is highly attractive, as here chemical (and physical) concepts of molecular reactivity, molecular design, and even metal catalysis are connected to aspects of materials science. In this Account, we will show how CuAAC reactions of multivalent components can be used as a tool for self-healing materials, achieving cross-linking at low temperatures (exploiting concepts of autocatalysis or internal chelation within the bulk CuAAC and systematic optimization of the efficiency of the used Cu(I) catalysts). Encapsulation strategies to separate the click components by micro- and nanoencapsulation are required in this context. Consequently, the examples reported here describe chemical concepts to realize more efficient and faster click reactions in self-healing polymeric materials. Thus, enhanced chain diffusion in (hyper

Abalone water-soluble matrix for self-healing biomineralization of tooth defects.

Science.gov (United States)

Wen, Zhenliang; Chen, Jingdi; Wang, Hailiang; Zhong, Shengnan; Hu, Yimin; Wang, Zhili; Zhang, Qiqing

2016-10-01

Enamel cannot heal by itself if damaged. Hydroxyapatite (HAP) is main component of human enamel. Formation of enamel-like materials for healing enamel defects remains a challenge. In this paper, we successfully isolated the abalone water-soluble matrix (AWSM) with 1.53wt% the abalone water-soluble protein (AWSPro) and 2.04wt% the abalone water-soluble polysaccharide (AWSPs) from abandoned abalone shell, and self-healing biomineralization of tooth defects was successfully achieved in vitro. Based on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), hot field emission scanning electron microscopy (HFESEM) and energy dispersive spectrometer (EDS) analysis, the results showed that the AWSM can efficiently induce remineralization of HAP. The enamel-like HAP was successfully achieved onto etched enamel's surface due to the presence of the AWSM. Moreover, the remineralized effect of eroded enamel was growing with the increase of the AWSM. This study provides a solution to the resource waste and environmental pollution caused by abandoned abalone shell, and we provides a new method for self-healing remineralization of enamel defects by AWSM and develops a novel dental material for potential clinical dentistry application. Copyright © 2016 Elsevier B.V. All rights reserved.

Solid state self-healing system: Effects of using PDGEBA, PVC and PVA as linear healing agents

Science.gov (United States)

Muhamad, Noor Nabilah; Jamil, Mohd. Suzeren Md.; Abdullah, Shahrum

2014-09-01

The solid state self-healing system was obtained by employing a thermosetting epoxy resin, into which a thermoplastic is dissolved. In this study, the effect of healing efficiency was investigated by using different thermoplastic polymers which are poly(bisphenol-A-co-epichlorohydrin), polyvinyl chloride and polyvinyl alcohol as healing agents. Healing was achieved by heating the fractured resins to a specific temperature i.e. above their glass transition temperature (Tg) which obtained from dynamic mechanical analysis (DMA) to mobilize the polymeric chains of the healing agent. The curing reaction in the epoxy resins were characterized by means of Fourier transform infrared spectroscopy (FTIR). Izod impact test was been performed to demonstrate self-healing of the different specimens. Under test, it was found that healable resin with PDGEBA has highest healing efficiency followed by PVC and PVA, with 63%, 35% and 18% of average percentage healing efficiencies respectively. These results are due to the different solubility parameters of the thermoset/network and thermoplastic polymer which led to the phase separation. Morphological studies prove the fracture-healing process and morphological properties of the resins.

Repeated self-healing of microvascular carbon fibre reinforced polymer composites

International Nuclear Information System (INIS)

Coope, T S; Trask, R S; Bond, I P; Wass, D F

2014-01-01

A self-healing, high performance, carbon fibre reinforced polymer (CFRP) composite is demonstrated by embedding a Lewis-acid catalytic curing agent within a laminate, manufactured using out of autoclave (OOA) composite manufacturing methods. Two configurations of healing agent delivery, pre-mixed and autonomous mixing, are investigated via injection of a healing agent through bio-inspired microvascular channels exposed on Mode I fractured crack planes. Healing is effected when an epoxy resin-solvent healing agent mixture reaches the boundary of embedded solid-state scandium(III) triflate (Sc(OTf) 3 ) catalyst, located on the crack plane, to initiate the ring-opening polymerisation (ROP) of epoxides. Tailored self-healing agents confer high healing efficiency values after multiple healing cycles (69–108%) to successfully mitigate against crack propagation within the composite microstructure. (paper)

Self-healing sandwich structures incorporating an interfacial layer with vascular network

International Nuclear Information System (INIS)

Chen, Chunlin; Peters, Kara; Li, Yulong

2013-01-01

A self-healing capability specifically targeted for sandwich composite laminates based on interfacial layers with built-in vascular networks is presented. The self-healing occurs at the facesheet–core interface through an additional interfacial layer to seal facesheet cracks and rebond facesheet–core regions. The efficacy of introducing the self-healing system at the facesheet–core interface is evaluated through four-point bend and edgewise compression testing of representative foam core sandwich composite specimens with impact induced damage. The self-healing interfacial layer partially restored the specific initial stiffness, doubling the residual initial stiffness as compared to the control specimen after the impact event. The restoration of the ultimate specific skin strength was less successful. The results also highlight the critical challenge in self-healing of sandwich composites, which is to rebond facesheets which have separated from the core material. (paper)

Design and testing of tubular polymeric capsules for self-healing of concrete

Science.gov (United States)

Araújo, M.; Van Tittelboom, K.; Feiteira, J.; Gruyaert, E.; Chatrabhuti, S.; Raquez, J.-M.; Šavija, B.; Alderete, N.; Schlangen, E.; De Belie, N.

2017-10-01

Polymeric healing agents have proven their efficiency to heal cracks in concrete in an autonomous way. However, the bottleneck for valorisation of self-healing concrete with polymeric healing agents is their encapsulation. In the present work, the suitability of polymeric materials such as poly(methyl methacrylate) (PMMA), polystyrene (PS) and poly(lactic acid) (PLA) as carriers for healing agents in self-healing concrete has been evaluated. The durability of the polymeric capsules in different environments (demineralized water, salt water and simulated concrete pore solution) and their compatibility with various healing agents have been assessed. Next, a numerical model was used to simulate capsule rupture when intersected by a crack in concrete and validated experimentally. Finally, two real-scale self-healing concrete beams were made, containing the selected polymeric capsules (with the best properties regarding resistance to concrete mixing and breakage upon crack formation) or glass capsules and a reference beam without capsules. The self-healing efficiency was determined after crack creation by 3-point-bending tests.

Novel routes to liquid-based self-healing polymer systems

NARCIS (Netherlands)

Mookhoek, S.D.

2010-01-01

Inspired by the current state-of-the-art and the progressing advancements in the field of self-healing materials, this thesis addresses several novel routes to advance the concept of liquid-based self-healing polymer systems. This thesis presents the concept and characterisation of a one-component

A comprehensive review on self-healing of asphalt materials: Mechanism, model, characterization and enhancement.

Science.gov (United States)

Sun, Daquan; Sun, Guoqiang; Zhu, Xingyi; Guarin, Alvaro; Li, Bin; Dai, Ziwei; Ling, Jianming

2018-05-09

Self-healing has great potential to extend the service life of asphalt pavement, and this capability has been regarded as an important strategy when designing a sustainable infrastructure. This review presents a comprehensive summary of the state-of-the-art investigations concerning the self-healing mechanism, model, characterization and enhancement, ranging from asphalt to asphalt pavement. Firstly, the self-healing phenomenon as a general concept in asphalt materials is analyzed including its definition and the differences among self-healing and some viscoelastic responses. Additionally, the development of self-healing in asphalt pavement design is introduced. Next, four kinds of possible self-healing mechanism and corresponding models are presented. It is pointed out that the continuum thermodynamic model, considering the whole process from damage initiation to healing recovery, can be a promising study field. Further, a set of self-healing multiscale characterization methods from microscale to macroscale as well as computational simulation scale, are summed up. Thereinto, the computational simulation shows great potential in simulating the self-healing behavior of asphalt materials from mechanical and molecular level. Moreover, the factors influencing self-healing capability are discussed, but the action mechanisms of some factors remain unclear and need to be investigated. Finally, two extrinsic self-healing technologies, induction heating and capsule healing, are recommended as preventive maintenance applications in asphalt pavement. In future, more effective energy-based healing systems or novel material-based healing systems are expected to be developed towards designing sustainable long-life asphalt pavement. Copyright © 2017 Elsevier B.V. All rights reserved.

Cementitious composite materials with improved self-healing potential

Directory of Open Access Journals (Sweden)

Cornelia BAERA

2015-12-01

Full Text Available Cement-based composites have proved, over the time, certain abilities of self-healing the damages (cracks and especially microcracs that occur within their structure. Depending on the level of damage and of the composite type in which this occurs, the self - healing process (SH can range from crack closing or crack sealing to the stage of partial or even complete recovery of material physical - mechanical properties. The aim of this paper is to present the general concept of Engineered Cementitious Composites (ECCs with their unique properties including their self-healing (SH capacity, as an innovative direction for a global sustainable infrastructure. The experimental steps initiated for the development in Romania of this unique category of materials, using materials available on the local market, are also presented.

Self-healing of Bessel-like beams with longitudinally dependent cone angles

International Nuclear Information System (INIS)

Litvin, I; Burger, L; Forbes, A

2015-01-01

Bessel beams have been extensively studied, but to date have been created over a finite region inside the laboratory. Recently Bessel-like beams with longitudinally dependent cone angles have been introduced allowing for a potentially infinite quasi non-diffracting propagation region. Here we show that such beams can self-heal. Moreover, in contrast to Bessel beams where the self-healing distance is constant, here the self-healing distance is dependent on where the obstruction is placed in the field, with the distance increasing as the Bessel-like beam propagates farther. We outline the theoretical concept for this self-healing and confirm it experimentally. (paper)

Autonomous stimulus triggered self-healing in smart structural composites

International Nuclear Information System (INIS)

Norris, C J; White, J A P; McCombe, G; Chatterjee, P; Bond, I P; Trask, R S

2012-01-01

Inspired by the ability of biological systems to sense and autonomously heal damage, this research has successfully demonstrated the first autonomous, stimulus triggered, self-healing system in a structural composite material. Both the sensing and healing mechanisms are reliant on microvascular channels incorporated within a laminated composite material. For the triggering mechanism, a single air filled vessel was pressurized, sealed and monitored. Upon drop weight impact (10 J), delamination and microcrack connectivity between the pressurized vessel and those open to ambient led to a pressure loss which, with the use of a suitable sensor, triggered a pump to deliver a healing agent to the damage zone. Using this autonomous healing approach, near full recovery of post-impact compression strength was achieved (94% on average). A simplified alternative system with healing agent continuously flowing through the vessels, akin to blood flow, was found to offer 100% recovery of the material’s virgin strength. Optical microscopy and ultrasonic C-scanning provided further evidence of large-scale infusion of matrix damage with the healing agent. The successful implementation of this bioinspired technology could substantially enhance the integrity and reliability of aerospace structures, whilst offering benefits through improved performance/weight ratios and extended lifetimes. (paper)

Microencapsulation of Self Healing Agents for Corrosion Control Coatings

Science.gov (United States)

Jolley, S. T.; Li, W.; Buhrow, J. W.; Calle, L. M.

2011-01-01

Corrosion, the environmentally induced degradation of materials, is a very costly problem that has a major impact on the global economy. Results from a 2-year breakthrough study released in 2002 by the U.S. Federal Highway Administration (FHWA) showed that the total annual estimated direct cost associated with metallic corrosion in nearly every U.S. industry sector was a staggering $276 billion, approximately 3.1% of the nation's Gross Domestic Product (GOP). Corrosion protective coatings are widely used to protect metallic structures from the detrimental effects of corrosion but their effectiveness can be seriously compromised by mechanical damage, such as a scratch, that exposes the metallic substrate. The incorporation of a self healing mechanism into a corrosion control coating would have the potential to significantly increase its effectiveness and useful lifetime. This paper describes work performed to incorporate a number of microcapsule-based self healing systems into corrosion control coatings. The work includes the preparation and evaluation of self-healing systems based on curable epoxy, acrylate, and siloxane resins, as well as, microencapsulated systems based on passive, solvent born, healing agent delivery. The synthesis and optimization of microcapsule-based self healing systems for thin coating (less than 100 micron) will be presented.

Microencapsulation of self-healing agents containing a fluorescent dye

Directory of Open Access Journals (Sweden)

J. K. Lee

2013-01-01

Full Text Available Two different self-healing agent candidates, endo-dicyclopentadiene (endo-DCPD and 5-ethylidene-2-norbornene (ENB, containing a fluorescent dye surrounded by a melamine–urea–formaldehyde (MUF shell were microencapsulated by in-situ polymerization and the resulting microcapsules were characterized in this work. The microcapsules showed a narrow size distribution with a spherical shape and rough outer and smooth inner surfaces for both healing agent systems. Shell thicknesses of the microcapsules were ~880±80 nm for endo-DCPD and ~620±60 nm for ENB. The incorporation of a fluorescent dye as tracer into self-healing agents did not disturb the formation of microcapsules. The release of self-healing liquid into the induced crack from ruptured microcapsules in an epoxy coating layer was observed using a fluorescence microscopy. The use of a fluorescent dye is very effective in the observation of a damage site.

A cost-effective bacteria-based self-healing cementitious composite for low-temperature marine applications

NARCIS (Netherlands)

Palin, D.

2017-01-01

Bacteria-based self-healing concrete is an innovative self-healing materials approach, whereby bacteria embedded in concrete can form a crack healing mineral precipitate. Structures made from self-healing concrete promise longer service lives, with associated economic benefits [1]. Despite concretes

Novel Diels-Alder based self-healing epoxies for aerospace composites

Science.gov (United States)

Coope, T. S.; Turkenburg, D. H.; Fischer, H. R.; Luterbacher, R.; van Bracht, H.; Bond, I. P.

2016-08-01

Epoxy resins containing Diels-Alder (DA) furan and maleimide moieties are presented with the capability to self-heal after exposure to an external heat source. A conventional epoxy amine system has been combined with furfuryl and maleimide functional groups in a two-step process, to avoid major side-reactions, and the concentration of a thermo-reversibly binding cross-linker was considered to balance thermoset and thermoplastic behaviours, and the subsequent self-healing performance. In the context of self-repair technologies an inbuilt ‘intrinsic’ self-healing system is deemed favourable as the healing agent can be placed in known ‘hot spot’ regions (i.e. skin-stringer run outs, ply drops and around drilled holes) where operational damage predominately occurs in load bearing aerospace structures. In this study, the mechanical and self-healing performance of furan functionalised epoxy resins containing varying amounts (10, 20, 30 or 40 pph) of bismaleimide were investigated using a bulk epoxy polymer tapered double cantilever beam test specimen geometry. Two forms, a thin film and a bulk material, were evaluated to account for future integration methods into fibre reinforced polymer (FRP) composites. The highest healing efficiency, with respect to the obtained initial load value, was observed from the 20 pph bulk material derivative. The polymers were successful in achieving consistent multiple (three) healing cycles when heated at 150 °C for 5 min. This novel investigated DA material exhibits favourable processing characteristics for FRP composites as preliminary studies have shown successful coextrution with reinforcing fibres to form free standing films and dry fibre impregnation.

Characterization and modeling of three-dimensional self-healing shape memory alloy-reinforced metal-matrix composites

Energy Technology Data Exchange (ETDEWEB)

Manuel, Michele Viola [University of Florida, Gainesville; Zhu, Pingping [Northwestern University, Evanston; Newman, John A. [NASA Langely Research Center (LaRC), Virginia; Wright, M Clara [NASA Kennedy Space Center, FL; Brinson, L Catherine [Northwestern University, Evanston; Kesler, Michael S. [ORNL

2016-09-10

In this paper, three-dimensional metal-matrix composites (MMCs) reinforced by shape memory alloy (SMA) wires are modeled and simulated, by adopting an SMA constitutive model accounting for elastic deformation, phase transformation and plastic behavior. A modeling method to create composites with pre-strained SMA wires is also proposed to improve the self-healing ability. Experimental validation is provided with a composite under three-point bending. This modeling method is applied in a series of finite element simulations to investigate the self-healing effects in pre-cracked composites, especially the role of the SMA reinforcement, the softening property of the matrix, and the effect of pre-strain in the SMA. The results demonstrate that SMA reinforcements provide stronger shape recovery ability than other, non-transforming materials. The softening property of the metallic matrix and the pre-strain in SMA are also beneficial to help crack closure and healing. This modeling approach can serve as an efficient tool to design SMA-reinforced MMCs with optimal self-healing properties that have potential applications in components needing a high level of reliability.

The microstructure of capsule containing self-healing materials: A micro-computed tomography study

Energy Technology Data Exchange (ETDEWEB)

Van Stappen, Jeroen, E-mail: Jeroen.Vanstappen@ugent.be [UGCT/PProGRess, Dept. of Geology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent (Belgium); SIM vzw, Technologiepark 935, B-9052 Zwijnaarde (Belgium); Bultreys, Tom [UGCT/PProGRess, Dept. of Geology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent (Belgium); Gilabert, Francisco A. [Mechanics of Materials and Structures, Dept. of Materials Science and Engineering, Ghent University, Technologiepark Zwijnaarde 903, B-9052 Zwijnaarde (Belgium); SIM vzw, Technologiepark 935, B-9052 Zwijnaarde (Belgium); Hillewaere, Xander K.D. [Polymer Chemistry Research Group, Dept. of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent (Belgium); SIM vzw, Technologiepark 935, B-9052 Zwijnaarde (Belgium); Gómez, David Garoz [Mechanics of Materials and Structures, Dept. of Materials Science and Engineering, Ghent University, Technologiepark Zwijnaarde 903, B-9052 Zwijnaarde (Belgium); SIM vzw, Technologiepark 935, B-9052 Zwijnaarde (Belgium); Van Tittelboom, Kim [Magnel Laboratory for Concrete Research, Dept. of Structural Engineering, Ghent University, Technologiepark Zwijnaarde 904, B-9052 Ghent (Belgium); Dhaene, Jelle [UGCT/Radiation Physics, Dept. of Physics and Astronomy, Ghent University, Proeftuinstraat 86, B-9000 Ghent (Belgium); De Belie, Nele [Magnel Laboratory for Concrete Research, Dept. of Structural Engineering, Ghent University, Technologiepark Zwijnaarde 904, B-9052 Ghent (Belgium); Van Paepegem, Wim [Mechanics of Materials and Structures, Dept. of Materials Science and Engineering, Ghent University, Technologiepark Zwijnaarde 903, B-9052 Zwijnaarde (Belgium); Du Prez, Filip E. [Polymer Chemistry Research Group, Dept. of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent (Belgium); Cnudde, Veerle [UGCT/PProGRess, Dept. of Geology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent (Belgium)

2016-09-15

Autonomic self-healing materials are materials with built-in (micro-) capsules or vessels, which upon fracturing release healing agents in order to recover the material's physical and mechanical properties. In order to better understand and engineer these materials, a thorough characterization of the material's microstructural behavior is essential and often overlooked. In this context, micro-computed tomography (μCT) can be used to investigate the three dimensional distribution and (de)bonding of (micro-) capsules in their native state in a polymer system with self-healing properties. Furthermore, in-situ μCT experiments in a self-healing polymer and a self-healing concrete system can elucidate the breakage and leakage behavior of (micro-) capsules at the micrometer scale. While challenges related to image resolution and contrast complicate the characterization in specific cases, non-destructive 3D imaging with μCT is shown to contribute to the understanding of the link between the microstructure and the self-healing behavior of these complex materials. - Highlights: • μCT imaging allows for the analysis of microcapsule distribution patterns in self-healing materials. • μCT allows for qualitative and quantitative measurements of healing agent release from carriers in self-healing materials. • Experimental set-ups can be optimized by changing chemical compounds in the system to ensure maximum quality imaging.

Analytical study on the self-healing property of Bessel beam

Science.gov (United States)

Chu, X.

2012-10-01

With the help of Babinet principle, an analytical expression for the self-healing of Bessel beam is derived by using the Gaussian absorption function to describe the obstacle. Based on the analytical expression, the self-healing properties of Bessel beam are studied. It shows that Bessel beam has the ability to reconstruct its beam shape disturbed by an obstacle. However, during the self-healing process, not only the intensity of the beam behind the obstacle but also the other part will be affected by the obstruction. Meanwhile, the highlight spot, which intensity is larger than that without the obstacle will appear, and the size and strength of the highlight spot is determined by the size of the obstacle. From the change of Poynting vector and Babinet principle, the physical interpretations for the self-healing ability, the effects of the obstruction on the other part and the appearance of highlight spot are given.

Facile preparation of self-healing superhydrophobic CeO2 surface by electrochemical processes

Science.gov (United States)

Nakayama, Katsutoshi; Hiraga, Takuya; Zhu, Chunyu; Tsuji, Etsushi; Aoki, Yoshitaka; Habazaki, Hiroki

2017-11-01

Herein we report simple electrochemical processes to fabricate a self-healing superhydrophobic CeO2 coating on Type 304 stainless steel. The CeO2 surface anodically deposited on flat stainless steel surface is hydrophilic, although high temperature-sintered and sputter-deposited CeO2 surface was reported to be hydrophobic. The anodically deposited hydrophilic CeO2 surface is transformed to hydrophobic during air exposure. Specific accumulation of contaminant hydrocarbon on the CeO2 surface is responsible for the transformation to hydrophobic state. The deposition of CeO2 on hierarchically rough stainless steel surface produces superhydrophobic CeO2 surface, which also shows self-healing ability; the surface changes to superhydrophilic after oxygen plasma treatment but superhydrophobic state is recovered repeatedly by air exposure. This work provides a facile method for preparing a self-healing superhydrophobic surface using practical electrochemical processes.

Development of an autonomous setup for evaluating self healing capability of asphalt mixtures

NARCIS (Netherlands)

Qiu, J.; Molenaar, A.A.A.; Van de Ven, M.F.C.; Wu, S.

2012-01-01

It is a well known fact that asphalt mixtures have self healing capabilities. Yet most of the self healing investigations are carried out using complex and time consuming fatigue tests. In order to investigate the self healing capability in a simple and efficient manner, a beam on elastic foundation

Electrosprayed Multi-Core Alginate Microcapsules as Novel Self-Healing Containers.

Science.gov (United States)

Hia, Iee Lee; Pasbakhsh, Pooria; Chan, Eng-Seng; Chai, Siang-Piao

2016-10-03

Alginate microcapsules containing epoxy resin were developed through electrospraying method and embedded into epoxy matrix to produce a capsule-based self-healing composite system. These formaldehyde free alginate/epoxy microcapsules were characterized via light microscope, field emission scanning electron microscope, fourier transform infrared spectroscopy and thermogravimetric analysis. Results showed that epoxy resin was successfully encapsulated within alginate matrix to form porous (multi-core) microcapsules with pore size ranged from 5-100 μm. The microcapsules had an average size of 320 ± 20 μm with decomposition temperature at 220 °C. The loading capacity of these capsules was estimated to be 79%. Under in situ healing test, impact specimens showed healing efficiency as high as 86% and the ability to heal up to 3 times due to the multi-core capsule structure and the high impact energy test that triggered the released of epoxy especially in the second and third healings. TDCB specimens showed one-time healing only with the highest healing efficiency of 76%. The single healing event was attributed by the constant crack propagation rate of TDCB fracture test. For the first time, a cost effective, environmentally benign and sustainable capsule-based self-healing system with multiple healing capabilities and high healing performance was developed.

Fracture behaviour of a self-healing microcapsule-loaded epoxy system

Directory of Open Access Journals (Sweden)

2011-03-01

Full Text Available The effect of temperature on the fracture behaviour of a microcapsule-loaded epoxy matrix was investigated. Microencapsulated epoxy and mercaptan-derivative healing agents were incorporated into an epoxy matrix to produce a polymer composite capable of self-healing. Maximum fracture loads were measured using the double-torsion method. Thermal aging at 55 and 110°C for 17 hours [hrs] was applied to heal the pre-cracked samples. The addition of microcapsules appeared to increase significantly the load carrying capacity of the epoxy after healing. Once healed, the composites achieved as much as 93–171% of its virgin maximum fracture load at 18, 55 and 110°C. The fracture behavior of the microcapsule- loaded epoxy matrix was influenced by the healing temperature. The high self-healing efficiency may be attributed to the result of the subsurface micro-crack pinning or deviation, and to a stronger microencapsulated epoxy and mercaptanderivative binder than that of the bulk epoxy. The results show that the healing temperature has a significant effect on recovery of load transferring capability after fracture.

Effect of blast furnace slag on self-healing of microcracks in cementitious materials

International Nuclear Information System (INIS)

Huang, Haoliang; Ye, Guang; Damidot, Denis

2014-01-01

The physico-chemical process of self-healing in blast furnace slag cement paste was investigated in this paper. With a high slag content i.e., 66% in cement paste and saturated Ca(OH) 2 solution as activator, it was found that the reaction products formed in cracks are composed of C-S-H, ettringite, hydrogarnet and OH–hydrotalcite. The fraction of C-S-H in the reaction products is much larger than the other minerals. Large amount of ettringite formed in cracks indicates the leaching of SO 4 2− ions from the bulk paste and consequently the recrystallization. Self-healing proceeds fast within 50 h and then slows down. According to thermodynamic modeling, when the newly formed reaction products are carbonated, the filling fraction of crack increases first and then decreases. Low soluble minerals such as silica gel, gibbsite and calcite are formed. Compared to Portland cement paste, the potential of self-healing in slag cement paste is higher when the percentage of slag is high. - Highlights: • Self-healing reaction products in slag cement paste were characterized. • Self-healing reaction products formed in time were quantified with image analysis. • Self-healing in slag cement paste was simulated with a reactive transport model. • Effect of carbonation on self-healing was investigated by thermodynamic modeling. • Effect of slag on self-healing was discussed based on experiments and simulation

X-ray computed microtomography of three-dimensional microcracks and self-healing in engineered cementitious composites

International Nuclear Information System (INIS)

Fan, Shuai; Li, Mo

2015-01-01

Concrete cracking and deterioration can potentially be addressed by innovative self-healing cementitious materials, which can autogenously regain transport properties and mechanical characteristics after the damage self-healing process. For the development of such materials, it is crucial, but challenging, to precisely characterize the extent and quality of self-healing due to a variety of factors. This study adopted x-ray computed microtomography (μCT) to derive three-dimensional morphological data on microcracks before and after healing in engineered cementitious composite (ECC). Scanning electron microscope and energy dispersive x-ray spectroscopy were also used to morphologically and chemically analyze the healing products. This work showed that the evolution of the microcrack 3D structure due to self-healing in cementitious materials can be directly and quantitatively characterized by μCT. A detailed description of the μCT image analysis method applied to ECC self-healing was presented. The results revealed that the self-healing extent and rate strongly depended on initial surface crack width, with smaller crack width favoring fast and robust self-healing. We also found that the self-healing mechanism in cementitious materials is dependent on crack depth. The region of a crack close to the surface (from 0 to around 50–150 μm below the surface) can be sealed quickly with crystalline precipitates. However, at greater depths the healing process inside the crack takes a significantly longer time to occur, with healing products more likely resulting from continued hydration and pozzolanic reactions. Finally, the μCT method was compared with other self-healing characterization methods, with discussions on its importance in generating new scientific knowledge for the development of robust self-healing cementitious materials. (paper)

Performance characteristics of a self-sealing/self-healing barrier

International Nuclear Information System (INIS)

McGregor, R.G.; Stegemann, J.A.

1997-01-01

Environment Canada and the Netherlands Energy Research Foundation are co-developers of a patented Self-Sealing/Self-Healing (SS/SH) Barrier system for containment of wastes which is licensed to Water Technology International Corporation. The SS/SH Barrier is intended for use as either a liner or cover for landfills, contaminated sites, secondary containment areas, etc., in the industrial, chemical, mining and municipal sectors, and also as a barrier to hydraulic flow for the transportation and construction industry. The SS/SH Barrier's most significant feature is its capability for self-repair in the event of a breach. By contrast, conventional barrier systems, such as clay, geomembrane, or geosynthetic clay liners can not be repaired without laborious excavation and reconstruction. Laboratory investigations have shown that the SS/SH Barrier concept will function with a variety of reactive materials. Self-Sealing/Self-Healing Barriers are cost competitive and consistently exhibit hydraulic conductivities ranging from 10 -9 to 10 -13 m/s, which decrease with time. These measurements meet or exceed the recommended hydraulic conductivity required by EPA for clay liners ( -9 m/s) used in landfills and hazardous waste sites. Results of mineralogical examination of the seal, diffusion testing, hydraulic conductivity measurement, and durability testing, including wet/dry, freeze/thaw cycling and leachate compatibility are also presented

Self-complementary circular codes in coding theory.

Science.gov (United States)

Fimmel, Elena; Michel, Christian J; Starman, Martin; Strüngmann, Lutz

2018-04-01

Self-complementary circular codes are involved in pairing genetic processes. A maximal [Formula: see text] self-complementary circular code X of trinucleotides was identified in genes of bacteria, archaea, eukaryotes, plasmids and viruses (Michel in Life 7(20):1-16 2017, J Theor Biol 380:156-177, 2015; Arquès and Michel in J Theor Biol 182:45-58 1996). In this paper, self-complementary circular codes are investigated using the graph theory approach recently formulated in Fimmel et al. (Philos Trans R Soc A 374:20150058, 2016). A directed graph [Formula: see text] associated with any code X mirrors the properties of the code. In the present paper, we demonstrate a necessary condition for the self-complementarity of an arbitrary code X in terms of the graph theory. The same condition has been proven to be sufficient for codes which are circular and of large size [Formula: see text] trinucleotides, in particular for maximal circular codes ([Formula: see text] trinucleotides). For codes of small-size [Formula: see text] trinucleotides, some very rare counterexamples have been constructed. Furthermore, the length and the structure of the longest paths in the graphs associated with the self-complementary circular codes are investigated. It has been proven that the longest paths in such graphs determine the reading frame for the self-complementary circular codes. By applying this result, the reading frame in any arbitrary sequence of trinucleotides is retrieved after at most 15 nucleotides, i.e., 5 consecutive trinucleotides, from the circular code X identified in genes. Thus, an X motif of a length of at least 15 nucleotides in an arbitrary sequence of trinucleotides (not necessarily all of them belonging to X) uniquely defines the reading (correct) frame, an important criterion for analyzing the X motifs in genes in the future.

Assessment of Composite Delamination Self-Healing Under Cyclic Loading

Science.gov (United States)

O'Brien, T. Kevin

2009-01-01

Recently, the promise of self-healing materials for enhanced autonomous durability has been introduced using a micro-encapsulation technique where a polymer based healing agent is encapsulated in thin walled spheres and embedded into a base polymer along with a catalyst phase. For this study, composite skin-stiffener flange debonding specimens were manufactured from composite prepreg containing interleaf layers with a polymer based healing agent encapsulated in thin-walled spheres. Constant amplitude fatigue tests in three-point bending showed the effect of self-healing on the fatigue response of the skin-stiffener flange coupons. After the cycling that created debonding, fatigue tests were held at the mean load for 24 hours. For roughly half the specimens tested, when the cyclic loading was resumed a decrease in compliance (increase in stiffness) was observed, indicating that some healing had occurred. However, with continued cycling, the specimen compliance eventually increased to the original level before the hold, indicating that the damage had returned to its original state. As was noted in a prevoius study conducted with specimens tested under monotonically increasing loads to failure, healing achieved via the micro-encapsulation technique may be limited to the volume of healing agent available relative to the crack volume.

Thermally driven self-healing using copper nanofiber heater

Science.gov (United States)

Lee, Min Wook; Jo, Hong Seok; Yoon, Sam S.; Yarin, Alexander L.

2017-07-01

Nano-textured transparent heaters made of copper nanofibers (CuNFs) are used to facilitate accelerated self-healing of bromobutyl rubber (BIIR). The heater and BIIR layer are separately deposited on each side of a transparent flexible polyethylene terephthalate (PET) substrate. A pre-notched crack on the BIIR layer was bridged due to heating facilitated by CuNFs. In the corrosion test, a cracked BIIR layer covered a steel substrate. An accelerated self-healing of the crack due to the transparent copper nanofiber heater facilitated an anti-corrosion protective effect of the BIIR layer.

Multifunctional Self-Healing and Morphing Composites

National Research Council Canada - National Science Library

Duenas, T; Bolanos, E; Murphy, E; Mal, A; Wudl, F; Schaffner, C; Wang, Y; Hahn, H. T; Ooi, T. K; Jha, A

2006-01-01

.... Proof of concept was demonstrated showing that a low volume-fraction (5-10%) of magnetic particles is sufficient for enabling self-healing of an approximate 150 micron x 5000 micron crack in a mendomer polymer using inductive heating...

Self-Healing, High-Permittivity Silicone Dielectric Elastomer

DEFF Research Database (Denmark)

Madsen, Frederikke Bahrt; Yu, Liyun; Skov, Anne Ladegaard

2016-01-01

possesses high dielectric permittivity and consists of an interpenetrating polymer network of silicone elastomer and ionic silicone species that are cross-linked through proton exchange between amines and acids. The ionically cross-linked silicone provides self-healing properties after electrical breakdown...... or cuts made directly to the material due to the reassembly of the ionic bonds that are broken during damage. The dielectric elastomers presented in this paper pave the way to increased lifetimes and the ability of dielectric elastomers to survive millions of cycles in high-voltage conditions....

Self healing phenomena in concretes and masonry mortars: A microscopic study

NARCIS (Netherlands)

Nijland, T.G.; Larbi, J.A.; Hees, R.P.J. van; Lubelli, B.A.; Rooij, M.R. de

2007-01-01

A microscopic survey of over 1000 of samples of concrete and masonry mortars from structures in the Netherlands shows that, in practice, self healing occurs in historic lime and lime – puzzolana mortars, in contrast to modern cement bound concretes and mortars. Self healing may be effected by the

High-Temperature Self-Healing and Re-Adhering Geothermal Well Cement Composites

Science.gov (United States)

Pyatina, T.; Sugama, T.; Boodhan, Y.; Nazarov, L.

2017-12-01

Self-healing cementitious materials are particularly attractive for the cases where damaged areas are difficult to locate and reach. High-temperature geothermal wells with aggressive environments impose most difficult conditions on cements that must ensure durable zonal isolation under repeated thermal, chemical and mechanical stresses. The present work evaluates matrix and carbon steel (CS) - cement interface self-healing and re-adhering properties of various inorganic cementitious composites under steam, alkali carbonate or brine environments at 270-300oC applicable to geothermal wells. The composite materials included blends based on Ordinary Portland Cement (OPC) and natural zeolites and alkali or phosphate activated composites of Calcium Aluminate Cement (CAC) with fly ash, class F. Class G cement blend with crystalline silica was used as a baseline. Compressive-strength and bond-strength recoveries were examined to evaluate self-healing and re-adhering properties of the composites after repeated crush tests followed by 5-day healing periods in these environments. The optical and scanning electron microscopes, X-ray diffraction, Fourier Transform infrared, Raman spectroscopy and EDX measurements were used to identify phases participating in the strengths recoveries and cracks filling processes. Amorphous silica-rich- and small-size crystalline phases played an important role in the healing of the tested composites in all environments. Possible ways to enhance self-healing properties of cementitious composites under conditions of geothermal wells were identified.

Self-Healing Characteristics of Damaged Rock Salt under Different Healing Conditions

Directory of Open Access Journals (Sweden)

Lin Li

2013-08-01

Full Text Available Salt deposits are commonly regarded as ideal hosts for geologic energy reservoirs. Underground cavern construction-induced damage in salt is reduced by self-healing. Thus, studying the influencing factors on such healing processes is important. This research uses ultrasonic technology to monitor the longitudinal wave velocity variations of stress-damaged rock salts during self-recovery experiments under different recovery conditions. The influences of stress-induced initial damage, temperature, humidity, and oil on the self-recovery of damaged rock salts are analyzed. The wave velocity values of the damaged rock salts increase rapidly during the first 200 h of recovery, and the values gradually increase toward stabilization after 600 h. The recovery of damaged rock salts is subjected to higher initial damage stress. Water is important in damage recovery. The increase in temperature improves damage recovery when water is abundant, but hinders recovery when water evaporates. The presence of residual hydraulic oil blocks the inter-granular role of water and restrains the recovery under triaxial compression. The results indicate that rock salt damage recovery is related to the damage degree, pore pressure, temperature, humidity, and presence of oil due to the sealing integrity of the jacket material.

Overview of recent work on self-healing in cementitious materials

Directory of Open Access Journals (Sweden)

Lv, Z.

2014-12-01

Full Text Available Cracks, especially microcracks, in concrete are of paramount importance to the durability and the service life of cementitious composite. However, the self-healing technology, including autogenous healing and autonomous healing, is expected to be one of effective tools to overcome this boring problem. In this paper, we focus on the autogenous healing of concrete material and a few of recent works of autonomous healing are also mentioned. The durability and the mechanical properties improved by the self-healing phenomenon are reviewed from experimental investigation and practical experience. Several aspects of researches, such as autogenous healing capability of an innovative concrete incorporated geo-materials, self-healing of engineered cementitious composite and fire-damaged concrete, effect of mineral and admixtures on mechanism and efficiency of self-healing concrete are summarized to evaluate the presented progresses in the past several years and to outline the perspective for the further developments. Moreover, a special emphasis is given on the analytical models and computer simulation method of the researches of self-healing in cementitious materials.Las fisuras, y sobre todo las microfisuras, tienen una gran repercusión en la durabilidad y en la vida útil de los materiales cementantes. Ante este problema, la tecnología de la autorreparación, tanto autógena como autónoma, se presenta como una solución eficaz. El artículo se centra en la reparación autógena del hormigón, así como en algunos trabajos recientes sobre la reparación autónoma. Se describen las mejoras de las propiedades de durabilidad y de resistencia que proporciona la técnica del hormigón autorreparable, tanto desde el punto de vista de la investigación experimental como del de la experiencia práctica. A fin de evaluar los avances logrados en los últimos años y de trazar las grandes líneas de desarrollo futuro, se resumen varios de los aspectos

Synthesis of a new hardener agent for self-healing epoxy resins

Science.gov (United States)

Raimondo, Marialuigia; Guadagno, Liberata; Naddeo, Carlo; Longo, Pasquale; Mariconda, Annaluisa; Agovino, Anna

2014-05-01

Actually, the development of smart composites capable of self-repair in aeronautical structures is still at the planning stage owing to complex issues to overcome. One of the critical points in the development of self-healing epoxy resin is related to the impossibility to employ primary amines as hardeners. In this paper, the synthesis of a new hardener for self-healing resins is shown together with applicability conditions/ranges.

Self-healing of cracks in Ag joining layer for die-attachment in power devices

Energy Technology Data Exchange (ETDEWEB)

Chen, Chuantong, E-mail: chenchuantong@sanken.osaka-u.ac.jp; Nagao, Shijo; Suganuma, Katsuaki; Jiu, Jinting; Zhang, Hao; Sugahara, Tohru [Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047 (Japan); Iwashige, Tomohito; Sugiura, Kazuhiko; Tsuruta, Kazuhiro [Research Division 3, Denso Corporation, Komenoki-cho, Minamiyama 500-1, Nissin, Aichi 470-0111 (Japan)

2016-08-29

Sintered silver (Ag) joining has attracted significant interest in power devices modules for its ability to form stable joints with a porous interconnection layer. A function for the self-healing of cracks in sintered porous Ag interlayers at high temperatures is discovered and reported here. A crack which was prepared on a Ag joining layer was closed after heating at 200 °C in air. The tensile strength of pre-cracked Ag joining layer specimens recovers to the value of non-cracked specimens after heating treatment. Transmission electron microscopy (TEM) was used to probe the self-healing mechanism. TEM images and electron diffraction patterns show that a large quantity of Ag nanoparticles formed at the gap with the size less than 10 nm, which bridges the crack in the self-healing process. This discovery provides additional motivation for the application of Ag as an interconnection material for power devices at high temperature.

Modeling Self-Healing of Concrete Using Hybrid Genetic Algorithm-Artificial Neural Network.

Science.gov (United States)

Ramadan Suleiman, Ahmed; Nehdi, Moncef L

2017-02-07

This paper presents an approach to predicting the intrinsic self-healing in concrete using a hybrid genetic algorithm-artificial neural network (GA-ANN). A genetic algorithm was implemented in the network as a stochastic optimizing tool for the initial optimal weights and biases. This approach can assist the network in achieving a global optimum and avoid the possibility of the network getting trapped at local optima. The proposed model was trained and validated using an especially built database using various experimental studies retrieved from the open literature. The model inputs include the cement content, water-to-cement ratio (w/c), type and dosage of supplementary cementitious materials, bio-healing materials, and both expansive and crystalline additives. Self-healing indicated by means of crack width is the model output. The results showed that the proposed GA-ANN model is capable of capturing the complex effects of various self-healing agents (e.g., biochemical material, silica-based additive, expansive and crystalline components) on the self-healing performance in cement-based materials.

Self-Healing, Inflatable, Rigidizable Shelter

Science.gov (United States)

Haight, Andrea; Gosau, Jan-Michael; Dixit, Anshu; Gleeson, Dan

2012-01-01

An inflatable, rigidizable shelter system was developed based on Rigi dization on Command (ROC) technology incorporating not only the requ ired low-stowage volume and lightweight character achieved from an i nflatable/rigidizable system, but also a self-healing foam system inc orporated between the rigidizable layers of the final structure to m inimize the damage caused by any punctures to the structure.

Transformation in Dang-ki Healing: The Embodied Self and Perceived Legitimacy.

Science.gov (United States)

Lee, Boon-Ooi

2016-09-01

Since spirit possession in mediumship and shamanism resembles psychotic symptoms, early researchers perceived spirit mediums and shamans as psychiatric patients whose psychopathology was culturally sanctioned. However, other researchers have not only challenged this assumption, but also proposed that spirit possession has transformative benefits. The idiom of spirit possession provides cultural meanings for spirit mediums and shamans to express and transform their personal experiences. The present case study focuses on dang-ki healing, a form of Chinese mediumship practiced in Singapore, in which a deity possesses a human (i.e., dang-ki) to offer aid to supplicants. This study seeks to explore whether involvement in dang-ki healing is transformative; and if so, how the dang-ki's transformation is related to his self and the perceived legitimacy of his mediumship. At a shrine, I interviewed 20 participants, including a male dang-ki, 10 temple assistants, and nine clients. The results obtained were supportive of the therapeutic nature of spirit possession. First, there is a relationship between his self-transformation and the perceived legitimacy of his mediumship. As his clients and community have recognized his spirit possession as genuine, and the healing power of his possessing god, he is able to make use of mediumship as a means for spiritual development. Second, he has developed his spirituality by internalizing his god's positive traits (e.g., compassion). Deities worshipped in dang-ki healing can be conceptualized as ideal selves who represent a wide range of positive traits and moral values of Chinese culture. Thus, the possession of a deity is the embodiment of an ideal self. Finally, the dang-ki's transformation may run parallel to his god's transformation. In Chinese religions, gods have to constantly develop their spirituality even though they are already gods. An understanding of the god's spiritual development further sheds light on the dang-ki's self-transformation.

Bioinspired engineering study of Plantae vascules for self-healing composite structures

Science.gov (United States)

Trask, R. S.; Bond, I. P.

2010-01-01

This paper presents the first conceptual study into creating a Plantae-inspired vascular network within a fibre-reinforced polymer composite laminate, which provides an ongoing self-healing functionality without incurring a mass penalty. Through the application of a ‘lost-wax’ technique, orthogonal hollow vascules, inspired by the ‘ray cell’ structures found in ring porous hardwoods, were successfully introduced within a carbon fibre-reinforced epoxy polymer composite laminate. The influence on fibre architecture and mechanical behaviour of single vascules (located on the laminate centreline) when aligned parallel and transverse to the local host ply was characterized experimentally using a compression-after-impact test methodology. Ultrasonic C-scanning and high-resolution micro-CT X-ray was undertaken to identify the influence of and interaction between the internal vasculature and impact damage. The results clearly show that damage morphology is influenced by vascule orientation and that a 10 J low-velocity impact damage event is sufficient to breach the vasculature; a prerequisite for any subsequent self-healing function. The residual compressive strength after a 10 J impact was found to be dependent upon vascule orientation. In general, residual compressive strength decreased to 70 per cent of undamaged strength when vasculature was aligned parallel to the local host ply and a value of 63 per cent when aligned transverse. This bioinspired engineering study has illustrated the potential that a vasculature concept has to offer in terms of providing a self-healing function with minimum mass penalty, without initiating premature failure within a composite structure. PMID:19955122

Self-Healing Structural Materials for Damage Tolerant Aerospace Vehicles

Data.gov (United States)

National Aeronautics and Space Administration — The proposed  effort describes how to develop novel lightweight, self-healing systems where self-repair is induced by the forces imparted by the damage event itself....

Chloride transport under compressive load in bacteria-based self-healing concrete

NARCIS (Netherlands)

Binti Md Yunus, B.; Schlangen, E.; Jonkers, H.M.

2015-01-01

An experiment was carried out in this study to investigate the effect of compressive load on chloride penetration in self-healing concrete containing bacterial-based healing agent. Bacteria-based healing agent with the fraction of 2 mm – 4 mm of particles sizes were used in this contribution. ESEM

Development of self-healing polymers via amine–epoxy chemistry: I. Properties of healing agent carriers and the modelling of a two-part self-healing system

International Nuclear Information System (INIS)

Zhang, He; Yang, Jinglei

2014-01-01

Two types of healing agent carriers (microcapsules containing epoxy solution, referred to as EP-capsules, and etched hollow glass bubbles (HGBs) loaded with amine solution, referred to as AM-HGBs) used in self-healing epoxy systems were prepared and characterized in this study. The core percentages were measured at about 80 wt% and 33 wt% for EP-capsules and AM-HGBs, respectively. The loaded amine in AM-HGB, after incorporation into the epoxy matrix, showed high stability at ambient temperature, but diffused out gradually during heat treatment at 80 °C. The amount and the mass ratio of the two released healants at the crack plane were correlated with the size, concentration, and core percentage of the healing agent carriers. A simplified cubic array model for randomly distributed healing agent carriers was adopted to depict the longest diffusion distance of the released healants, which is inversely proportional to the cubic root of the carrier concentration. (papers)

Influence of the Microwave Heating Time on the Self-Healing Properties of Asphalt Mixtures

Directory of Open Access Journals (Sweden)

Jose Norambuena-Contreras

2017-10-01

Full Text Available This paper aims to evaluate the influence of the microwave heating time on the self-healing properties of fibre-reinforced asphalt mixtures. To this purpose, self-healing properties of dense asphalt mixtures with four different percentages of steel wool fibres were evaluated as the three-point bending strength before and after healing via microwave heating at four different heating times. Furthermore, the thermal behaviour of asphalt mixtures during microwave heating was also evaluated. With the aim of quantifying the efficiency of the repair process, ten damage-healing cycles were done in the test samples. In addition, self-healing results were compared with the fibre spatial distribution inside asphalt samples evaluated by CT-scans. Crack-size change on asphalt samples during healing cycles was also evaluated through optical microscopy. It was found that the heating time is the most influential variable on the healing level reached by the asphalt mixtures tested by microwave radiation. CT-Scans results proved that fibre spatial distribution into the asphalt mixtures play an important role in the asphalt healing level. Finally, it was concluded that 40 s was the optimum heating time to reach the highest healing levels with the lowest damage on the asphalt samples, and that heating times over 30 s can seal the cracks, thus achieving the self-healing of asphalt mixtures via microwave heating.

Self-Healing Superhydrophobic Materials Showing Quick Damage Recovery and Long-Term Durability.

Science.gov (United States)

Wang, Liming; Urata, Chihiro; Sato, Tomoya; England, Matt W; Hozumi, Atsushi

2017-09-26

Superhydrophobic coatings/materials are important for a wide variety of applications, but the majority of these man-made coatings/materials still suffer from poor durability because of their lack of self-healing ability. Here, we report novel superhydrophobic materials which can quickly self-heal from various severe types of damage. In this study, we used poly(dimethylsiloxane) (PDMS) infused with two liquids: trichloropropylsilane, which reacts with ambient moisture to self-assemble into grass-like microfibers (named silicone micro/nanograss) on the surfaces and low-viscosity silicone oil (SO), which remains within the PDMS matrices and acts as a self-healing agent. Because of the silicone micro/nanograss structures on the PDMS surfaces and the effective preserve/protection system of a large quantity of SO within the PDMS matrices, our superhydrophobic materials showed quick superhydrophobic recovery under ambient conditions (within 1-2 h) even after exposure to plasma (24 h), boiling water, chemicals, and outside environments. Such an ability is superior to the best self-healing superhydrophobic coatings/materials reported so far.

Microcapsule-Type Self-Healing Protective Coating for Cementitious Composites with Secondary Crack Preventing Ability.

Science.gov (United States)

Kim, Dong-Min; Yu, Hwan-Chul; Yang, Hye-In; Cho, Yu-Jin; Lee, Kwang-Myong; Chung, Chan-Moon

2017-01-26

A microcapsule-type self-healing protective coating with secondary crack preventing capability has been developed using a silanol-terminated polydimethylsiloxane (STP)/dibutyltin dilaurate (DD) healing agent. STP undergoes condensation reaction in the presence of DD to give a viscoelastic substance. STP- and DD-containing microcapsules were prepared by in-situ polymerization and interfacial polymerization methods, respectively. The microcapsules were characterized by Fourier-transform infrared (FT-IR) spectroscopy, optical microscopy, and scanning electron microscopy (SEM). The microcapsules were integrated into commercial enamel paint or epoxy coating formulations, which were applied on silicon wafers, steel panels, and mortar specimens to make dual-capsule self-healing protective coatings. When the STP/DD-based coating was scratched, self-healing of the damaged region occurred, which was demonstrated by SEM, electrochemical test, and water permeability test. It was also confirmed that secondary crack did not occur in the healed region upon application of vigorous vibration to the self-healing coating.

Microcapsule-Type Self-Healing Protective Coating for Cementitious Composites with Secondary Crack Preventing Ability

Directory of Open Access Journals (Sweden)

Dong-Min Kim

2017-01-01

Full Text Available A microcapsule-type self-healing protective coating with secondary crack preventing capability has been developed using a silanol-terminated polydimethylsiloxane (STP/dibutyltin dilaurate (DD healing agent. STP undergoes condensation reaction in the presence of DD to give a viscoelastic substance. STP- and DD-containing microcapsules were prepared by in-situ polymerization and interfacial polymerization methods, respectively. The microcapsules were characterized by Fourier-transform infrared (FT-IR spectroscopy, optical microscopy, and scanning electron microscopy (SEM. The microcapsules were integrated into commercial enamel paint or epoxy coating formulations, which were applied on silicon wafers, steel panels, and mortar specimens to make dual-capsule self-healing protective coatings. When the STP/DD-based coating was scratched, self-healing of the damaged region occurred, which was demonstrated by SEM, electrochemical test, and water permeability test. It was also confirmed that secondary crack did not occur in the healed region upon application of vigorous vibration to the self-healing coating.

Novel approach to make concrete structures self-healing using porous network concrete

NARCIS (Netherlands)

Sangadji, S.; Schlangen, E.

2012-01-01

Many researchers proposed self healing mechanism using hollow fibres and or microcapsule containing a modifying agent dispersed in the concrete to prolong its service life and make it more durable. A novel self healing concrete concept is proposed in this paper by using porous network concrete

Functionalized Agarose Self-Healing Ionogels Suitable for Supercapacitors.

Science.gov (United States)

Trivedi, Tushar J; Bhattacharjya, Dhrubajyoti; Yu, Jong-Sung; Kumar, Arvind

2015-10-12

Agarose has been functionalized (acetylated/carbanilated) in an ionic liquid (IL) medium of 1-butyl-3-methylimidazolium acetate at ambient conditions. The acetylated agarose showed a highly hydrophobic nature, whereas the carbanilated agarose could be dissolved in water as well as in the IL medium. Thermoreversible ionogels were obtained by cooling the IL sols of carbanilated agarose at room temperature. The ionogel prepared from a protic-aprotic mixed-IL system (1-butyl-3-methylimidazolium chloride and N-(2-hydroxyethyl)ammonium formate) demonstrated a superior self-healing property, as confirmed from rheological measurements. The superior self-healing property of such an ionogel has been attributed to the unique inter-intra hydrogen-bonding network of functional groups inserted in the agarose. The ionogel was tested as a flexible solid electrolyte for an activated-carbon-based supercapacitor cell. The measured specific capacitance was found to be comparable with that of a liquid electrolyte system at room temperature and was maintained for up to 1000 charge-discharge cycles. Such novel functionalized-biopolymer self-healing ionogels with flexibility and good conductivity are desirable for energy-storage devices and electronic skins with superior lifespans and robustness. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of self-healing ability of Ce–V conversion coating on AZ31 magnesium alloy

Directory of Open Access Journals (Sweden)

Xiao Jiang

2016-09-01

Full Text Available This study investigated the influence of cerium nitrate in vanadate solutions on the properties of Ce–V conversion coatings on AZ31 magnesium alloys, and evaluated the self-healing behavior of the Ce–V conversion coating for AZ31 magnesium alloy. The results showed that the additions of cerium nitrate prevented pentavalent vanadium from reducing to tetravalent vanadium in the coatings during conversion reaction process. Adding appropriate cerium nitrate to vanadate solution led to a thicker coating with a more compact CeVO4 layer. The corrosion behavior of the Ce–V conversion coating was investigated by the electrochemical tests and the scratch immersion test in 3.5 wt.% NaCl solution. The self-healing ability of the coating was confirmed from all tests. The surface analysis revealed that the self-healing effect of the Ce–V conversion coating was only provided by the release and migration of vanadium compounds.

Local electrochemical evaluation of a self-healing coating based on encapsulated healing-agent

NARCIS (Netherlands)

González-García, Y.; García, S.J.; Fischer, H.R.; Hughes, A.E.; Mol, J.M.C.

2011-01-01

In this work local electrochemical techniques are introduced as powerful and complementary techniques for the in-situ evaluation of self-healing systems applied for the protection of metals against corrosion. Scanning vibrating electrode technique (SVET) and scanning electrochemical microscopy

Initial Self-Healing Temperatures of Asphalt Mastics Based on Flow Behavior Index.

Science.gov (United States)

Li, Chao; Wu, Shaopeng; Tao, Guanyu; Xiao, Yue

2018-05-29

Increasing temperature is a simple and convenient method to accelerate the self-healing process of bitumen. However, bitumen may not achieve the healing capability at lower temperature, and may be aged if temperature is too high. In addition, the bitumen is mixed with mineral filler and formed as asphalt mastic in asphalt concrete, so it is more accurate to study the initial self-healing from the perspective of asphalt mastic. The primary purpose of this research was to examine the initial self-healing temperature of asphalt mastic, which was determined by the flow behavior index obtained from the flow characteristics. Firstly, the texture and geometry characteristics of two fillers were analyzed, and then the initial self-healing temperature of nine types of asphalt mastic, pure bitumen (PB) and styrene-butadiene-styrene (SBS) modified bitumen were determined by the flow behavior index. Results demonstrate that the average standard deviation of gray-scale texture value of limestone filler (LF) is 21.24% lower than that of steel slag filler (SSF), showing that the steel slag filler has a better particle distribution and geometry characteristics. Also the initial self-healing temperatures of asphalt mastics with 0.2, 0.4 and 0.6 LF-PB volume ratio are 46.5 °C, 47.2 °C and 49.4 °C, which are 1.4 °C, 0.8 °C and 0.4 °C higher than that of asphalt mastics with SSF-PB, but not suitable for the evaluation of asphalt mastic contained SBS modified bitumen because of unique structure and performance of SBS.

Self-Healing Supramolecular Hydrogels Based on Reversible Physical Interactions

Directory of Open Access Journals (Sweden)

Satu Strandman

2016-04-01

Full Text Available Dynamic and reversible polymer networks capable of self-healing, i.e., restoring their mechanical properties after deformation and failure, are gaining increasing research interest, as there is a continuous need towards extending the lifetime and improving the safety and performance of materials particularly in biomedical applications. Hydrogels are versatile materials that may allow self-healing through a variety of covalent and non-covalent bonding strategies. The structural recovery of physical gels has long been a topic of interest in soft materials physics and various supramolecular interactions can induce this kind of recovery. This review highlights the non-covalent strategies of building self-repairing hydrogels and the characterization of their mechanical properties. Potential applications and future prospects of these materials are also discussed.

A computational model for the flow of resin in self-healing composites

Science.gov (United States)

Hall, J.; Qamar, I. P. S.; Rendall, T. C. S.; Trask, R. S.

2015-03-01

To explore the flow characteristics of healing agent leaving a vascular network and infusing a damage site within a fibre reinforced polymer composite, a numerical model of healing agent flow from an orifice has been developed using smoothed particle hydrodynamics. As an initial validation the discharge coefficient for low Reynolds number flow from a cylindrical tank is calculated numerically, using two different viscosity formulations, and compared to existing experimental data. Results of this comparison are very favourable; the model is able to reproduce experimental results for the discharge coefficient in the high Reynolds number limit, together with the power-law behaviour for low Reynolds numbers. Results are also presented for a representative delamination geometry showing healing fluid behaviour and fraction filled inside the delamination for a variety of fluid viscosities. This work provides the foundations for the vascular self-healing community in calculating not only the flow rate through the network, but also, by simulating a representative damage site, the final location of the healing fluid within the damage site in order to assess the improvement in local and global mechanical properties and thus healing efficiency.

Self-healing polyurethane/attapulgite nanocomposites based on disulfide bonds and shape memory effect

Energy Technology Data Exchange (ETDEWEB)

Xu, Yurun; Chen, Dajun, E-mail: cdj@dhu.edu.cn

2017-07-01

Nanocomposites with remarkable enhanced mechanical properties have attracted great research efforts recently. In this work, a series of self-healing polyurethane/attapulgite nanocomposites were prepared by solution blending. Introducing self-healing ability and attapulgite (AT) reinforcement simultaneously led to prolonged material lifetime and enhanced mechanical properties. Scanning electron microscope (SEM) observation indicated that AT could achieve a uniform dispersion in polyurethane matrix when AT content was relatively low. The influences on mechanical properties were evaluated by tensile test. Results showed that incorporating an appropriate content of AT would lead to an enhanced tensile properties. The interactions between AT and polyurethane matrix were studied by effective cross-linking density calculation and Fourier transform infrared (FTIR) analysis. Results indicated that rich hydrogen bonds were formed between AT and polyurethane matrix. Displacement data was utilized to evaluate the influence on shape memory effect. With the incorporation of AT, deformation of the sample under external force was restrained. Meanwhile, closure of the scratches still can be accomplished during healing process. Results of healing test suggested that incorporating 1% of AT would also promote self-healing property. - Highlights: • Composites with both self-healing and enhanced mechanical property are prepared. • Healing mechanism relies on disulfide exchange reaction and shape memory effect. • Mechanical enhancement is caused by rich hydrogen bonds introduced by attapulgite.

Self-healing polyurethane/attapulgite nanocomposites based on disulfide bonds and shape memory effect

International Nuclear Information System (INIS)

Xu, Yurun; Chen, Dajun

2017-01-01

Nanocomposites with remarkable enhanced mechanical properties have attracted great research efforts recently. In this work, a series of self-healing polyurethane/attapulgite nanocomposites were prepared by solution blending. Introducing self-healing ability and attapulgite (AT) reinforcement simultaneously led to prolonged material lifetime and enhanced mechanical properties. Scanning electron microscope (SEM) observation indicated that AT could achieve a uniform dispersion in polyurethane matrix when AT content was relatively low. The influences on mechanical properties were evaluated by tensile test. Results showed that incorporating an appropriate content of AT would lead to an enhanced tensile properties. The interactions between AT and polyurethane matrix were studied by effective cross-linking density calculation and Fourier transform infrared (FTIR) analysis. Results indicated that rich hydrogen bonds were formed between AT and polyurethane matrix. Displacement data was utilized to evaluate the influence on shape memory effect. With the incorporation of AT, deformation of the sample under external force was restrained. Meanwhile, closure of the scratches still can be accomplished during healing process. Results of healing test suggested that incorporating 1% of AT would also promote self-healing property. - Highlights: • Composites with both self-healing and enhanced mechanical property are prepared. • Healing mechanism relies on disulfide exchange reaction and shape memory effect. • Mechanical enhancement is caused by rich hydrogen bonds introduced by attapulgite.

Self-healing of Micro-cracks in Engineered Cementitious Composites

Directory of Open Access Journals (Sweden)

Suryanto B.

2015-12-01

Full Text Available The performance of an Engineered Cementitious Composite (ECC to self-heal micro-cracks under a controlled laboratory environment is presented. Ten dog-bone shaped samples were prepared; five of them were preloaded to known strains and then left to heal in water in a temperature-controlled laboratory. Ultrasonic pulse velocity (UPV measurements were undertaken to monitor the crack-healing process. It was found that all samples exhibited recoveries in UPV and were able to recover to between 96.6% and 98% of their pre-test UPV values over a period of four weeks. An accelerated rate of healing was observed in the initial two-day period immediately following the preloading test.

Self healing in polymers and polymer composites. Concepts, realization and outlook: A review

Directory of Open Access Journals (Sweden)

2008-04-01

Full Text Available Formation of microcracks is a critical problem in polymers and polymer composites during their service in structural applications. Development and coalescence of microcracks would bring about catastrophic failure of the materials and then reduce their lifetimes. Therefore, early sensing, diagnosis and repair of microcracks become necessary for removing the latent perils. In this context, the materials possessing self-healing function are ideal for long-term operation. Self-repairing polymers and polymer composites have attracted increasing research interests. Attempts have been made to develop solutions in this field. The present article reviews state-of-art of the achievements on the topic. According to the ways of healing, the smart materials are classified into two categories: (i intrinsic self-healing ones that are able to heal cracks by the polymers themselves, and (ii extrinsic in which healing agent has to be pre-embedded. The advances in this field show that selection and optimization of proper repair mechanisms are prerequisites for high healing efficiency. It is a challenging job to either invent new polymers with inherent crack repair capability or integrate existing materials with novel healing system.

Processing and performance of self-healing materials

International Nuclear Information System (INIS)

Tan, P S; Bhattacharyya, D; Zhang, M Q

2009-01-01

Two self-healing methods were implemented into composite materials with self-healing capabilities, using hollow glass fibres (HGF) and microencapsulated epoxy resin with mercaptan as the hardener. For the HGF approach, two perpendicular layers of HGF were put into an E-glass/epoxy composite, and were filled with coloured epoxy resin and hardener. The HGF samples had a novel ball indentation test method done on them. The samples were analysed using micro-CT scanning, confocal microscopy and penetrant dye. Micro-CT and confocal microscopy produced limited success, but their viability was established. Penetrant dye images showed resin obstructing flow of dye through damage regions, suggesting infiltration of resin into cracks. Three-point bend tests showed that overall performance could be affected by the flaws arising from embedding HGF in the material. For the microcapsule approach, samples were prepared for novel double-torsion tests used to generate large cracks. The samples were compared with pure resin samples by analysing them using photoelastic imaging and scanning electron microscope (SEM) on crack surfaces. Photoelastic imaging established the consolidation of cracks while SEM showed a wide spread of microcapsules with their distribution being affected by gravity. Further double-torsion testing showed that healing recovered approximately 24% of material strength.

Bio-reinforced self-healing concrete using magnetic iron oxide nanoparticles.

Science.gov (United States)

Seifan, Mostafa; Sarmah, Ajit K; Ebrahiminezhad, Alireza; Ghasemi, Younes; Samani, Ali Khajeh; Berenjian, Aydin

2018-03-01

Immobilization has been reported as an efficient technique to address the bacterial vulnerability for application in bio self-healing concrete. In this study, for the first time, magnetic iron oxide nanoparticles (IONs) are being practically employed as the protective vehicle for bacteria to evaluate the self-healing performance in concrete environment. Magnetic IONs were successfully synthesized and characterized using different techniques. The scanning electron microscope (SEM) images show the efficient adsorption of nanoparticles to the Bacillus cells. Microscopic observation illustrates that the incorporation of the immobilized bacteria in the concrete matrix resulted in a significant crack healing behavior, while the control specimen had no healing characteristics. Analysis of bio-precipitates revealed that the induced minerals in the cracks were calcium carbonate. The effect of magnetic immobilized cells on the concrete water absorption showed that the concrete specimens supplemented with decorated bacteria with IONs had a higher resistance to water penetration. The initial and secondary water absorption rates in bio-concrete specimens were 26% and 22% lower than the control specimens. Due to the compatible behavior of IONs with the concrete compositions, the results of this study proved the potential application of IONs for developing a new generation of bio self-healing concrete.

Electrical and Structural Origin of Self-Healing Phenomena in Pentacene Thin Films.

Science.gov (United States)

Kang, Evan S H; Zhang, Hongbin; Donner, Wolfgang; von Seggern, Heinz

2017-04-01

Self-healing induced by structural phase transformation is demonstrated using pentacene field-effect transistors. During the self-healing process, the electrical properties at the pentacene interfaces improve due to the phase transformation from monolayer phase to thin-film phase. Enhanced mobility is confirmed by first-principles calculations. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Initial Self-Healing Temperatures of Asphalt Mastics Based on Flow Behavior Index

Directory of Open Access Journals (Sweden)

Chao Li

2018-05-01

Full Text Available Increasing temperature is a simple and convenient method to accelerate the self-healing process of bitumen. However, bitumen may not achieve the healing capability at lower temperature, and may be aged if temperature is too high. In addition, the bitumen is mixed with mineral filler and formed as asphalt mastic in asphalt concrete, so it is more accurate to study the initial self-healing from the perspective of asphalt mastic. The primary purpose of this research was to examine the initial self-healing temperature of asphalt mastic, which was determined by the flow behavior index obtained from the flow characteristics. Firstly, the texture and geometry characteristics of two fillers were analyzed, and then the initial self-healing temperature of nine types of asphalt mastic, pure bitumen (PB and styrene-butadiene-styrene (SBS modified bitumen were determined by the flow behavior index. Results demonstrate that the average standard deviation of gray-scale texture value of limestone filler (LF is 21.24% lower than that of steel slag filler (SSF, showing that the steel slag filler has a better particle distribution and geometry characteristics. Also the initial self-healing temperatures of asphalt mastics with 0.2, 0.4 and 0.6 LF-PB volume ratio are 46.5 °C, 47.2 °C and 49.4 °C, which are 1.4 °C, 0.8 °C and 0.4 °C higher than that of asphalt mastics with SSF-PB, but not suitable for the evaluation of asphalt mastic contained SBS modified bitumen because of unique structure and performance of SBS.

Mechanoresponsive Healing Polymers

Science.gov (United States)

Gordon, Keith L. (Inventor); Siochi, Emilie J. (Inventor)

2018-01-01

Methods are provided to produce new mechanoresponsive healing systems. Additionally, various embodiments provide a two tier self-healing material system concept that provides a non-intrusive method to mitigate impact damage in a structure ranging from low velocity impact damage (e.g., crack damage) to high velocity impact damage (e.g., ballistic damage.) The various embodiments provide the mechanophore linked polymer PBG-BCB-PBG. The various embodiments provide methods for synthesizing PBG-BCB-PBG.

Self-healing of Fractures in Argillaceous Media from the Geomechanical Point of View

International Nuclear Information System (INIS)

Horseman, Steve

2001-01-01

Presently, there is no established theory describing fracture self-healing and self-sealing processes in mud-rocks (clays, mud-stones and shales) and no methodology to assess the conditions under which these processes might be important. The author suggests that the modified Cam-Clay approach provides a useful conceptual and theoretical framework for the analysis of the largely hydro-mechanical process of self-sealing. Three basic hypotheses are proposed and applied to the problem of fracture self-sealing in the repository EDZ and to the more general question of fault sealing. (author)

Research of the self-healing technologies in the optical communication network of distribution automation

Science.gov (United States)

Wang, Hao; Zhong, Guoxin

2018-03-01

Optical communication network is the mainstream technique of the communication networks for distribution automation, and self-healing technologies can improve the in reliability of the optical communication networks significantly. This paper discussed the technical characteristics and application scenarios of several network self-healing technologies in the access layer, the backbone layer and the core layer of the optical communication networks for distribution automation. On the base of the contrastive analysis, this paper gives an application suggestion of these self-healing technologies.

Nature's Mechanisms for Tough, Self-healing Polymers and Polymer Adhesives

Science.gov (United States)

Hansma, Paul

2007-03-01

Spider silk^2 and the natural polymer adhesives in abalone shells^3 and bone^4,5 can give us insights into nature's mechanisms for tough, self-healing polymers and polymer adhesives. The natural polymer adhesives in biomaterials have been optimized by evolution. An optimized polymer adhesive has five characteristics. 1) It holds together the strong elements of the composite. 2) It yields just before the strong elements would otherwise break. 3) It dissipates large amounts of energy as it yields. 4) It self heals after it yields. 5) It takes just a few percent by weight. Both natural polymer adhesives and silk rely on sacrificial bonds and hidden length for toughness and self-healing.^6 A relatively large energy, of order 100eV, is required to stretch a polymer molecule after a weak bond, a sacrificial bond, breaks and liberates hidden length, which was previously hidden, typically in a loop or folded domain, from whatever was stretching the polymer. The bond is called sacrificial if it breaks at forces well below the forces that could otherwise break the polymer backbone, typically greater than 1nN. In many biological cases, the breaking of sacrificial bonds has been found to be reversible, thereby also providing a ``self-healing'' property to the material.^2-4 Individual polymer adhesive molecules based on sacrificial bonds and hidden length can supply forces of order 300pN over distances of 100s of nanometers. Model calculations show that a few percent by weight of adhesives based on these principles could be optimized adhesives for high performance composite materials including nanotube and graphene sheet composites. ^2N. Becker, E. Oroudjev, S. Mutz et al., Nature Materials 2 (4), 278 (2003). ^3B. L. Smith, T. E. Schaffer, M. Viani et al., Nature 399 (6738), 761 (1999). ^4J. B. Thompson, J. H. Kindt, B. Drake et al., Nature 414 (6865), 773 (2001). ^5G. E. Fantner, T. Hassenkam, J. H. Kindt et al., Nature Materials 4, 612 (2005). ^6G. E. Fantner, E. Oroudjev, G

Optimization of process factors for self-healing vanadium-based conversion coating on AZ31 magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Li, Kun; Liu, Junyao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Lei, Ting, E-mail: tlei@mail.csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Xiao, Tao [2nd Xiangya Hospital, Central South University, Changsha 410011 (China)

2015-10-30

Highlights: • The optimum operating conditions were determined by an orthogonal experiment. • The coating is composed of oxides and hydroxides of V{sup 5+}, V{sup 4+} and Mg(OH){sub 2}. • The self-healing performance was investigated by cross-cut immersion test. • The vanadia conversion coating provided active corrosion protection to AZ31 alloy. - Abstract: A self-healing vanadium-based conversion coating was prepared on AZ31 magnesium alloy. The optimum operating conditions including vanadia solution concentration, pH and treating temperature for obtaining the best corrosion protective vanadia coatings and improved localized corrosion resistance to the magnesium substrate were determined by an orthogonal experiment design. Surface morphology and composition of the resultant conversion coatings were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The self-healing behavior of the coating was investigated by cross-cut immersion test and electrochemical impedance spectroscopy (EIS) measurements in 3.5% NaCl solution.

Optimization of process factors for self-healing vanadium-based conversion coating on AZ31 magnesium alloy

International Nuclear Information System (INIS)

Li, Kun; Liu, Junyao; Lei, Ting; Xiao, Tao

2015-01-01

Highlights: • The optimum operating conditions were determined by an orthogonal experiment. • The coating is composed of oxides and hydroxides of V"5"+, V"4"+ and Mg(OH)_2. • The self-healing performance was investigated by cross-cut immersion test. • The vanadia conversion coating provided active corrosion protection to AZ31 alloy. - Abstract: A self-healing vanadium-based conversion coating was prepared on AZ31 magnesium alloy. The optimum operating conditions including vanadia solution concentration, pH and treating temperature for obtaining the best corrosion protective vanadia coatings and improved localized corrosion resistance to the magnesium substrate were determined by an orthogonal experiment design. Surface morphology and composition of the resultant conversion coatings were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The self-healing behavior of the coating was investigated by cross-cut immersion test and electrochemical impedance spectroscopy (EIS) measurements in 3.5% NaCl solution.

Recycling and Self-Healing of Polybenzoxazines with Dynamic Sulfide Linkages.

Science.gov (United States)

Arslan, Mustafa; Kiskan, Baris; Yagci, Yusuf

2017-07-12

In this work, a recycling and self-healing strategy for polybenzoxazines through both S-S bond cleavage-reformation reaction and supramolecular attractions is described. Both recyclable and self-healable polybenzoxazines can be prepared from low cost chemicals with a simple procedure in only 30 minutes. For this purpose, inverse vulcanization of poly(propylene oxide)benzoxazine (PPOB) and diallybenzoxazine (B-al) with elemental sulfur was performed at 185 °C. The obtained cross-linked polymer films exhibited thermally driven recycling ability up to 5 cycles. Moreover, the self-healing ability of a test specimen was shown. Spectral characterizations, thermal stability and fracture toughness of the films were investigated after each recycling.

Indigenous Healing Practices and Self-Medication amongst ...

African Journals Online (AJOL)

Indigenous Healing Practices and Self-Medication amongst Pregnant Women in Cape Town, South Africa. Naeemah Abrahams, Rachel Jewkes, Zodumo Mvo. Abstract. This study was conducted in and around Cape Town, South Africa, at two primary obstetric facilities and in the antenatal clinics of two secondary hospitals.

Hermitian self-dual quasi-abelian codes

Directory of Open Access Journals (Sweden)

Herbert S. Palines

2017-12-01

Full Text Available Quasi-abelian codes constitute an important class of linear codes containing theoretically and practically interesting codes such as quasi-cyclic codes, abelian codes, and cyclic codes. In particular, the sub-class consisting of 1-generator quasi-abelian codes contains large families of good codes. Based on the well-known decomposition of quasi-abelian codes, the characterization and enumeration of Hermitian self-dual quasi-abelian codes are given. In the case of 1-generator quasi-abelian codes, we offer necessary and sufficient conditions for such codes to be Hermitian self-dual and give a formula for the number of these codes. In the case where the underlying groups are some $p$-groups, the actual number of resulting Hermitian self-dual quasi-abelian codes are determined.

Self-Healing Natural Rubber with Tailorable Mechanical Properties Based on Ionic Supramolecular Hybrid Network.

Science.gov (United States)

Xu, Chuanhui; Cao, Liming; Huang, Xunhui; Chen, Yukun; Lin, Baofeng; Fu, Lihua

2017-08-30

In most cases, the strength of self-healing supramolecular rubber based on noncovalent bonds is in the order of KPa, which is a challenge for their further applications. Incorporation of conventional fillers can effectively enhance the strength of rubbers, but usually accompanied by a sacrifice of self-healing capability due to that the filler system is independent of the reversible supramolecular network. In the present work, in situ reaction of methacrylic acid (MAA) and excess zinc oxide (ZnO) was realized in natural rubber (NR). Ionic cross-links in NR matrix were obtained by limiting the covalent cross-linking of NR molecules and allowing the in situ polymerization of MAA/ZnO. Because of the natural affinity between Zn 2+ ion-rich domains and ZnO, the residual nano ZnO participated in formation of a reversible ionic supramolecular hybrid network, thus having little obstructions on the reconstruction of ionic cross-links. Meanwhile, the well dispersed residual ZnO could tailor the mechanical properties of NR by changing the MAA/ZnO molar ratios. The present study thus provides a simple method to fabricate a new self-healing NR with tailorable mechanical properties that may have more potential applications.

Analytical Model for the Probability Characteristics of a Crack Penetrating Capsules in Capsule-Based Self-Healing Cementitious Materials

Directory of Open Access Journals (Sweden)

Zhong LV

2017-08-01

Full Text Available Autonomous crack healing using pre-embedded capsules containing healing agent is becoming a promising approach to restore the strength of damaged structures. In addition to the material properties, the size and volume fraction of capsules influence crack healing in the matrix. Understanding the crack and capsule interaction is critical in the development and design of structures made of capsule-based self-healing materials. Continuing our previous study, in this contribution a more practical rupturing mode of capsules characterizing the rupturing manner of capsules fractured by cracks in cementitious materials is presented, i.e., penetrating mode. With the underlying assumption that a crack penetrating capsules undoubtedly leads to crack healing, geometrical probability theory is employed to develop the quantitative relationship between crack size and capsule size, capsule concentration in capsule-based self-healing virtual cementitious material. Moreover, an analytical expression of probability of a crack penetrating with randomly dispersed capsules is developed in two-dimensional material matrix setup. The influences of the induced rupturing modes of capsules embedded on the self-healing efficiency are analyzed. Much attention is paid to compare the penetrating probability and the hitting probability, in order to assist the designer to make a choice of the optimal rupturing modes of capsules embedded. The accuracy of results of the theoretical model is also compared with Monte-Carlo numerical analysis of crack interacting with capsules. It shows that the developed probability characteristics of a crack interaction with capsules for different rupturing modes is helpful to provide guidelines for designer working with capsule-based self-healing cementitious materials.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16888

Self-Configuration and Self-Healing for Cognitive Optical Networks

OpenAIRE

Tronco, Tania Regina; Feres, Mariana Massimino; Cesar, Amilcar Careli; Rocha, Mônica de Lacerda

2013-01-01

In this article we propose a fuzzy controller, as an inference engine for cognitive optical networks, to take decisions about routing of new demands of lightpaths, considering physical layer impairments (Fuzzy Controlled-PLIARWA algorithm), selfconfiguration, self-healing and cross-layer optimization functionalities. The proposed algorithm has been tested in a metropolitan-scaled network. The preliminary results obtained are promising in terms of modularity, flexibility, ...

Epithelial self-healing is recapitulated by a 3D biomimetic E-cadherin junction

NARCIS (Netherlands)

Cohen, Daniel J.; Gloerich, Martijn; Nelson, W. James

2016-01-01

Epithelial monolayers undergo self-healing when wounded. During healing, cells collectively migrate into the wound site, and the converging tissue fronts collide and form a stable interface. To heal, migrating tissues must form cell-cell adhesions and reorganize from the front-rear polarity

Multiple self-healing squamous epithelioma of Ferguson-Smith

DEFF Research Database (Denmark)

Broesby-Olsen, Sigurd; Bygum, Anette; Gerdes, Anne-Marie

2008-01-01

Multiple self-healing squamous epithelioma of Ferguson-Smith (MSSE) is a rare autosomal dominantly inherited disease, almost exclusively reported in patients of Scottish origin, with recurrent, histologically malignant tumours that undergo spontaneous regression. We report clinical observations...

Microencapsulation of Self-healing Concrete Properties

Science.gov (United States)

2012-08-01

design and development. Other factors that can affect concrete and its lifespan include shrinkage , design flaws or poor quality of construction...possible shrinkage , design flaws or poor quality of construction materials, reinforced concrete will eventually develop cracks. Inevitable damage to...SELF-HEALING CONCRETE PROPERTIES N00244-l 0-G-0004 Sb. GRANT NUMBER Sc. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Sd. PROJECT NUMBER James Gilford III

Improving Kinetics of “Click-Crosslinking” for Self-Healing Nanocomposites by Graphene-Supported Cu-Nanoparticles

Directory of Open Access Journals (Sweden)

Neda Kargarfard

2017-12-01

Full Text Available Investigation of the curing kinetics of crosslinking reactions and the development of optimized catalyst systems is of importance for the preparation of self-healing nanocomposites, able to significantly extend their service lifetimes. Here we study different modified low molecular weight multivalent azides for a capsule-based self-healing approach, where self-healing is mediated by graphene-supported copper-nanoparticles, able to trigger “click”-based crosslinking of trivalent azides and alkynes. When monitoring the reaction kinetics of the curing reaction via reactive dynamic scanning calorimetry (DSC, it was found that the “click-crosslinking” reactivity decreased with increasing chain length of the according azide. Additionally, we could show a remarkable “click” reactivity already at 0 °C, highlighting the potential of click-based self-healing approaches. Furthermore, we varied the reaction temperature during the preparation of our tailor-made graphene-based copper(I catalyst to further optimize its catalytic activity. With the most active catalyst prepared at 700 °C and the optimized set-up of reactants on hand, we prepared capsule-based self-healing epoxy nanocomposites.

Multifunctional Polymers and Composites for Self-Healing Applications

Science.gov (United States)

2006-09-30

N,N’-dicyclohexylcarbodiimide (DCC) was obtained from Avocado . Reagent grade ether was purchased from Malinckrodt and anhydrous methylene chloride...several companies through sponsored research agreements to transition self-healing technology into the commercial market . These agreements include

Hydraulically amplified self-healing electrostatic actuators with muscle-like performance

Science.gov (United States)

Acome, E.; Mitchell, S. K.; Morrissey, T. G.; Emmett, M. B.; Benjamin, C.; King, M.; Radakovitz, M.; Keplinger, C.

2018-01-01

Existing soft actuators have persistent challenges that restrain the potential of soft robotics, highlighting a need for soft transducers that are powerful, high-speed, efficient, and robust. We describe a class of soft actuators, termed hydraulically amplified self-healing electrostatic (HASEL) actuators, which harness a mechanism that couples electrostatic and hydraulic forces to achieve a variety of actuation modes. We introduce prototypical designs of HASEL actuators and demonstrate their robust, muscle-like performance as well as their ability to repeatedly self-heal after dielectric breakdown—all using widely available materials and common fabrication techniques. A soft gripper handling delicate objects and a self-sensing artificial muscle powering a robotic arm illustrate the wide potential of HASEL actuators for next-generation soft robotic devices.

Fundamental Solution For The Self-healing Fracture Pulse

Science.gov (United States)

Nielsen, S.; Madariaga, R.

We find the analytical solution for a fundamental fracture mode in the form of a self- similar, self-healing pulse. The existence of such a fracture mode was strongly sug- gested by recent numerical findings but, to our knwledge, no formal proof had been proposed up to date. We present a two dimensional, anti-plane solution for fixed rup- ture and healing velocities, that satisfies both wave equation and stress conditions; we argue that such a solution is plausible even in the absence of rate-weakening in the friction, as an alternative to the classic crack solution. In practice, the impulsive mode rather than the expanding crack mode is selected depending on details of fracture initiation, and is therafter self-maintained. We discuss stress concentration, fracture energy, rupture velocity and compare them to the case of a crack. The analytical study is complemented by various numerical examples and comparisons. On more general grounds, we argue that an infinity of marginally stable fracture modes may exist other than the crack solution or the impulseive fracture described here.

pH-responsive self-healing injectable hydrogel based on N-carboxyethyl chitosan for hepatocellular carcinoma therapy.

Science.gov (United States)

Qu, Jin; Zhao, Xin; Ma, Peter X; Guo, Baolin

2017-08-01

property could prolong their lifetime during implantation and provide the advantage of minimally invasive surgery and high drug-loading ratio. This work reported the design of a series of pH-responsive self-healing injectable hydrogels based on N-carboxyethyl chitosan synthesized in aqueous solution and dibenzaldehyde-terminated poly(ethylene glycol) via a green approach, and demonstrated their potential as intelligent delivery vehicle of doxorubicin for hepatocellular carcinoma therapy via the pH-responsive nature of dynamic Schiff base. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Healing assessment of tile sets for error tolerance in DNA self-assembly.

Science.gov (United States)

Hashempour, M; Mashreghian Arani, Z; Lombardi, F

2008-12-01

An assessment of the effectiveness of healing for error tolerance in DNA self-assembly tile sets for algorithmic/nano-manufacturing applications is presented. Initially, the conditions for correct binding of a tile to an existing aggregate are analysed using a Markovian approach; based on this analysis, it is proved that correct aggregation (as identified with a so-called ideal tile set) is not always met for the existing tile sets for nano-manufacturing. A metric for assessing tile sets for healing by utilising punctures is proposed. Tile sets are investigated and assessed with respect to features such as error (mismatched tile) movement, punctured area and bond types. Subsequently, it is shown that the proposed metric can comprehensively assess the healing effectiveness of a puncture type for a tile set and its capability to attain error tolerance for the desired pattern. Extensive simulation results are provided.

Integral procedure to assess crack filling and mechanical contribution of polymer-based healing agent in encapsulation-based self-healing concrete

NARCIS (Netherlands)

Gilabert Villegas, Francisco Antonio; Van Tittelboom, Kim; Van Stappen, J.; Cnudde, Veerle; De Belie, Nele; Van Paepegem, Wim

2017-01-01

This work presents an experimental and numerical study to analyze the crack filling process in encapsulation-based self-healing concrete. A specimen consisting of two small concrete blocks has been designed containing capsules filled with a polyurethane-based healing agent. This design enables to

Self-healing of low-velocity impact damage in glass fabric/epoxy composites using an epoxy–mercaptan healing agent

International Nuclear Information System (INIS)

Yuan, Yan Chao; Qin, Shi Xiang; Ye, Yueping; Chen, Haibin; Wu, Jingshen; Rong, Min Zhi; Zhang, Ming Qiu; Yang, Gui Cheng

2011-01-01

Self-healing woven glass fabric-reinforced epoxy composite laminates were made by embedding epoxy- and mercaptan-loaded microcapsules. After being subjected to low-velocity impact, the laminates were able to heal the damage in an autonomic way at room temperature. The healing-induced reduction in the damaged areas was visualized using a scanning acoustic microscope. The rate of damage area reduction, which is closely related to the effect of crack rehabilitation and mechanical recovery, is a function of impact energy, content and size of the healing microcapsules. Minor damage, such as microcracks in the matrix, can be completely repaired by the healing system without manual intervention, including external pressure. Microcapsules with larger size and/or higher concentration are propitious for delivering more healing agent to cracked portions, while imposition of lateral pressure on damaged specimens forces the separated faces to approach each other. Both can improve the rate of damage area reduction in the case of severe damage

Self-healing of drying shrinkage cracks in cement-based materials incorporating reactive MgO

Science.gov (United States)

Qureshi, T. S.; Al-Tabbaa, A.

2016-08-01

Excessive drying shrinkage is one of the major issues of concern for longevity and reduced strength performance of concrete structures. It can cause the formation of cracks in the concrete. This research aims to improve the autogenous self-healing capacity of traditional Portland cement (PC) systems, adding expansive minerals such as reactive magnesium oxide (MgO) in terms of drying shrinkage crack healing. Two different reactive grades (high ‘N50’and moderately high ‘92-200’) of MgO were added with PC. Cracks were induced in the samples with restraining end prisms through natural drying shrinkage over 28 days after casting. Samples were then cured under water for 28 and 56 days, and self-healing capacity was investigated in terms of mechanical strength recovery, crack sealing efficiency and improvement in durability. Finally, microstructures of the healing materials were investigated using FT-IR, XRD, and SEM-EDX. Overall N50 mixes show higher expansion and drying shrinkage compared to 92-200 mixes. Autogenous self-healing performance of the MgO containing samples were much higher compared to control (only PC) mixes. Cracks up to 500 μm were sealed in most MgO containing samples after 28 days. In the microstructural investigations, highly expansive Mg-rich hydro-carbonate bridges were found along with traditional calcium-based, self-healing compounds (calcite, portlandite, calcium silicate hydrates and ettringite).

Self-Healing Phase Change Salogels with Tunable Gelation Temperature.

Science.gov (United States)

Karimineghlani, Parvin; Palanisamy, Anbazhagan; Sukhishvili, Svetlana A

2018-04-19

Chemically cross-linked polymer matrices have demonstrated strong potential for shape stabilization of molten phase change materials (PCM). However, they are not designed to be fillable and removable from a heat exchange module for an easy replacement with new PCM matrices and lack self-healing capability. Here, a new category of shapeable, self-healing gels, "salogels", is introduced. The salogels reversibly disassemble in a high-salinity environment of a fluid inorganic PCM [lithium nitrate trihydrate (LNH)], at a preprogrammed temperature. LNH was employed as a high latent heat PCM and simultaneously as a solvent, which supported the formation of a network of polyvinyl alcohol (PVA) chains via physical cross-linking through poly(amidoamine) dendrimers of various generations. The existence of hydrogen bonding and the importance of low-hydration state of PVA for the efficient gelation were experimentally confirmed. The thermal behavior of PCM salogels was highly reversible and repeatable during multiple heating/cooling cycles. Importantly, the gel-sol transition temperature could be precisely controlled within a range of temperature above LNH's melting point by the choice of dendrimer generation and their concentration. Shape stabilization and self-healing properties of the salogels, taken together with tunability of their temperature-induced fluidization make these materials attractive for thermal energy storage applications that require on-demand removal and replacement of used inorganic PCM salt hydrates.

Layer-by-Layer Assembly of Fluorine-Free Polyelectrolyte-Surfactant Complexes for the Fabrication of Self-Healing Superhydrophobic Films.

Science.gov (United States)

Wu, Mengchun; An, Ni; Li, Yang; Sun, Junqi

2016-11-29

Fluorine-free self-healing superhydrophobic films are of significance for practical applications because of their extended service life and cost-effective and eco-friendly preparation process. In this study, we report the fabrication of fluorine-free self-healing superhydrophobic films by layer-by-layer (LbL) assembly of poly(sodium 4-styrenesulfonate) (PSS)-1-octadecylamine (ODA) complexes (PSS-ODA) and poly(allylamine hydrochloride) (PAH)-sodium dodecyl sulfonate (SDS) (PAH-SDS) complexes. The wettability of the LbL-assembled PSS-ODA/PAH-SDS films depends on the film structure and can be tailored by changing the NaCl concentration in aqueous dispersions of PSS-ODA complexes and the number of film deposition cycles. The freshly prepared PSS-ODA/PAH-SDS film with micro- and nanoscaled hierarchical structures is hydrophilic and gradually changes to superhydrophobic in air because the polyelectrolyte-complexed ODA and SDS surfactants tend to migrate to the film surface to cover the film with hydrophobic alkyl chains to lower its surface energy. The large amount of ODA and SDS surfactants loaded in the superhydrophobic PSS-ODA/PAH-SDS films and the autonomic migration of these surfactants to the film surface endow the resultant superhydrophobic films with an excellent self-healing ability to restore the damaged superhydrophobicity. The self-healing superhydrophobic PSS-ODA/PAH-SDS films are mechanically robust and can be deposited on various flat and nonflat substrates. The LbL assembly of oppositely charged polyelectrolyte-surfactant complexes provides a new way for the fabrication of fluorine-free self-healing superhydrophobic films with satisfactory mechanical stability, enhanced reliability, and extended service life.

Assessment of Composite Delamination Self-Healing Via Micro-Encapsulation

Science.gov (United States)

O'Brien, T. Kevin; White, Scott R.

2008-01-01

Composite skin/stringer flange debond specimens manufactured from composite prepreg containing interleaf layers with a polymer based healing agent encapsulated in thin walled spheres were tested. As a crack develops and grows in the base polymer, the spheres fracture releasing the healing agent. The agent reacts with catalyst and polymerizes healing the crack. In addition, through-thickness reinforcement, in the form of pultruded carbon z-pins were included near the flange tips to improve the resistance to debonding. Specimens were manufactured with 14 plies in the skin and 10 plies in the stiffener flange. Three-point bend tests were performed to measure the skin/stiffener debonding strength and the recovered strength after healing. The first three tests performed indicated no healing following unloading and reloading. Micrographs showed that delaminations could migrate to the top of the interleaf layer due to the asymmetric loading, and hence, bypass most of the embedded capsules. For two subsequent tests, specimens were clamped in reverse bending before reloading. In one case, healing was observed as evidenced by healing agent that leaked to the specimen edge forming a visible "scar". The residual strength measured upon reloading was 96% of the original strength indicating healing had occurred. Hence, self-healing is possible in fiber reinforced composite material under controlled conditions, i.e., given enough time and contact with pressure on the crack surfaces. The micro-encapsulation technique may prove more robust when capsule sizes can be produced that are small enough to be embedded in the matrix resin without the need for using an interleaf layer. However, in either configuration, the amount of healing that can occur may be limited to the volume of healing agent available relative to the crack volume that must be filled.

Self-healing Li-Al layered double hydroxide conversion coating modified with aspartic acid for 6N01 Al alloy

Science.gov (United States)

Zhang, Caixia; Luo, Xiaohu; Pan, Xinyu; Liao, Liying; Wu, Xiaosong; Liu, Yali

2017-02-01

A self-healing Li-Al layered double hydroxide conversion coating (LCC) modified with aspartic acid (ALCC) was prepared on 6N01 Al alloy for corrosion protection. Scanning electron microscopy (SEM) showed that a compact thin film has been successfully formed on the alloy. X-ray diffraction (XRD) and FT-IR spectra proved that species of aspartic acid anions were successfully intercalated into LCC. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and neutral salt spray (NSS) testing showed that the resultant ALCC could provide effective corrosion protection for the Al alloy. During immersion of the ALCC-coated alloy in 3.5% NaCl solution, new film was formed in the area of artificially introduced scratch, indicating its self-healing capability. XPS results demonstrated that Cl- anions exchange partial Asp anions according to the change content of element on conversion coating. From the above results, the possible mechanism via exchange/self-assembly was proposed to illustrate the phenomenon of self-healing.

Investigation of self healing behaviour of asphalt mixes using beam on elastic foundation setup

NARCIS (Netherlands)

Qiu, J.; Molenaar, A.A.A.; Van de Ven, M.F.C.; Wu, S.; Yu, J.

2012-01-01

Self healing of asphalt mixes is known for more than four decades. However, it is a complex phenomenon which depends on the duration of the rest period, temperature, crack size, etc. In order to quantify the self healing behaviour of asphalt mixes, a test setup was proposed in this research using an

Epithelial self-healing is recapitulated by a 3D biomimetic E-cadherin junction

OpenAIRE

Cohen, Daniel J.; Gloerich, Martijn; Nelson, W. James

2016-01-01

Epithelial monolayers undergo self-healing when wounded. During healing, cells collectively migrate into the wound site, and the converging tissue fronts collide and form a stable interface. To heal, migrating tissues must form cell-cell adhesions and reorganize from the front-rear polarity characteristic of cell migration to the apicalbasal polarity of an epithelium. However, identifying the "stop signal" that induces colliding tissues to cease migrating and heal remains an open question. Ep...

Mimicking Bone Healing Process to Self Repair Concrete Structure Novel Approach Using Porous Network Concrete

NARCIS (Netherlands)

Sangadji, S.; Schlangen, H.E.J.G.

2013-01-01

To repair concrete cracks in difficult or dangerous conditions such as underground structures or hazardous liquid containers, self healing mechanism is a promising alternative method. This research aims to imitate the bone self healing process by putting porous concrete internally in the concrete

Self-healing Li-Al layered double hydroxide conversion coating modified with aspartic acid for 6N01 Al alloy

International Nuclear Information System (INIS)

Zhang, Caixia; Luo, Xiaohu; Pan, Xinyu; Liao, Liying; Wu, Xiaosong; Liu, Yali

2017-01-01

Highlights: • A self-healing chrome-free Li-Al layered double hydroxide conversion coating modified with Aspartic acid was prepared. • One-step conversion coating formed by simple immersion in a conversion solution for a short time and a low temperature. • The conversion coating had excellent corrosion resistance. • The possible mechanism via exchange/self-assembly of the conversion coating was proposed in this paper. - Abstract: A self-healing Li-Al layered double hydroxide conversion coating (LCC) modified with aspartic acid (ALCC) was prepared on 6N01 Al alloy for corrosion protection. Scanning electron microscopy (SEM) showed that a compact thin film has been successfully formed on the alloy. X-ray diffraction (XRD) and FT-IR spectra proved that species of aspartic acid anions were successfully intercalated into LCC. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and neutral salt spray (NSS) testing showed that the resultant ALCC could provide effective corrosion protection for the Al alloy. During immersion of the ALCC-coated alloy in 3.5% NaCl solution, new film was formed in the area of artificially introduced scratch, indicating its self-healing capability. XPS results demonstrated that Cl- anions exchange partial Asp anions according to the change content of element on conversion coating. From the above results, the possible mechanism via exchange/self-assembly was proposed to illustrate the phenomenon of self-healing.

Self-healing Li-Al layered double hydroxide conversion coating modified with aspartic acid for 6N01 Al alloy

Energy Technology Data Exchange (ETDEWEB)

Zhang, Caixia; Luo, Xiaohu; Pan, Xinyu; Liao, Liying; Wu, Xiaosong; Liu, Yali, E-mail: yaliliu@hnu.edu.cn

2017-02-01

Highlights: • A self-healing chrome-free Li-Al layered double hydroxide conversion coating modified with Aspartic acid was prepared. • One-step conversion coating formed by simple immersion in a conversion solution for a short time and a low temperature. • The conversion coating had excellent corrosion resistance. • The possible mechanism via exchange/self-assembly of the conversion coating was proposed in this paper. - Abstract: A self-healing Li-Al layered double hydroxide conversion coating (LCC) modified with aspartic acid (ALCC) was prepared on 6N01 Al alloy for corrosion protection. Scanning electron microscopy (SEM) showed that a compact thin film has been successfully formed on the alloy. X-ray diffraction (XRD) and FT-IR spectra proved that species of aspartic acid anions were successfully intercalated into LCC. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and neutral salt spray (NSS) testing showed that the resultant ALCC could provide effective corrosion protection for the Al alloy. During immersion of the ALCC-coated alloy in 3.5% NaCl solution, new film was formed in the area of artificially introduced scratch, indicating its self-healing capability. XPS results demonstrated that Cl- anions exchange partial Asp anions according to the change content of element on conversion coating. From the above results, the possible mechanism via exchange/self-assembly was proposed to illustrate the phenomenon of self-healing.

Atomic Origins of the Self-Healing Function in Cement–Polymer Composites

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Manh Thuong; Wang, Zheming; Rod, Kenton A.; Childers, Matthew I.; Fernandez, Carlos A.; Koech, Phillip K.; Bennett, Wendy D.; Rousseau, Roger J.; Glezakou, Vassiliki-Alexandra

2018-01-09

Motivated by recent advances in self-healing cement and epoxy polymer composites, we present a combined ab initio molecular dynamics and sum frequency generation (SFG) spectroscopy study of a calcium-silicate-hydrate/polymer interface. On stable, low-defect surfaces, the polymer only weakly adheres through coordination and hydrogen bonding interactions and can be easily mobilized towards defected surfaces. Conversely, on fractured surfaces, the polymer strongly anchors through ionic Ca-O bonds resulting from the deprotonation of polymer hydroxyl groups. In addition, polymer S-S groups are turned away from the cement/polymer interface, allowing for the self-healing function within the polymer. The overall elasticity and healing properties of these composites stem from a flexible hydrogen bonding network that can readily adapt to surface morphology. The theoretical vibrational signals associated with the proposed cement-polymer interfacial chemistry were confirmed experimentally by SFG spectroscopy.

Self healing of damage in Fe-based alloys

NARCIS (Netherlands)

Zhang, S.

2015-01-01

Steel components can exhibit premature and low-ductility creep fracture, when exposed to high temperatures for long times. The failure arises from the formation, growth and coalescence of ultra-fine cracks and cavities. Self healing of damage is a promising new approach to enhance the lifetime of

Epithelial self-healing is recapitulated by a 3D biomimetic E-cadherin junction.

Science.gov (United States)

Cohen, Daniel J; Gloerich, Martijn; Nelson, W James

2016-12-20

Epithelial monolayers undergo self-healing when wounded. During healing, cells collectively migrate into the wound site, and the converging tissue fronts collide and form a stable interface. To heal, migrating tissues must form cell-cell adhesions and reorganize from the front-rear polarity characteristic of cell migration to the apical-basal polarity of an epithelium. However, identifying the "stop signal" that induces colliding tissues to cease migrating and heal remains an open question. Epithelial cells form integrin-based adhesions to the basal extracellular matrix (ECM) and E-cadherin-mediated cell-cell adhesions on the orthogonal, lateral surfaces between cells. Current biological tools have been unable to probe this multicellular 3D interface to determine the stop signal. We addressed this problem by developing a unique biointerface that mimicked the 3D organization of epithelial cell adhesions. This "minimal tissue mimic" (MTM) comprised a basal ECM substrate and a vertical surface coated with purified extracellular domain of E-cadherin, and was designed for collision with the healing edge of an epithelial monolayer. Three-dimensional imaging showed that adhesions formed between cells, and the E-cadherin-coated MTM resembled the morphology and dynamics of native epithelial cell-cell junctions and induced the same polarity transition that occurs during epithelial self-healing. These results indicate that E-cadherin presented in the proper 3D context constitutes a minimum essential stop signal to induce self-healing. That the Ecad:Fc MTM stably integrated into an epithelial tissue and reduced migration at the interface suggests that this biointerface is a complimentary approach to existing tissue-material interfaces.

Simulation of self-healing of dolomitic lime mortar

NARCIS (Netherlands)

Lubelli, B.; Nijland, T.G.; Van Hees, R.P.J.

2011-01-01

In the present research a test procedure was set up to reproduce self-healing on lime-based (both pure calcium and magnesium-calcium) mortar specimens in laboratory. After few months testing, during which the specimens were subjected to wet-dry cycles, thin sections of the specimens were prepared

Fracturing and Self-Healing in the Boom Clay: Evidences and Further Studies

International Nuclear Information System (INIS)

Bernier, Frederic

2001-01-01

The Boom Clay is considered as a potential host-rock for the disposal of Belgian radioactive waste. During the sinking of a new shaft to extend the underground facility HADES, an important fracturing has been evidenced around the excavation. Fracturing was already observed previously but to a lesser extent. The low support pressure imposed by the primary shaft lining, combined with the large time over which this support condition held, has favoured the decompression of the clay massif through delayed effects, and therefore the development of fracturing. In the frame of the overall performance of a radioactive waste repository, it is of prime importance to understand the fracturing process induced by excavation in Boom Clay, as well as the self-healing process. Some self-healing evidences have been observed around the HADES underground laboratory but need further investigation to be confirmed. This will be done in the SELFRAC EC project (Fractures and Self-healing within the Excavation Disturbed Zone in clays)

Mussel-inspired immobilization of BN nanosheets onto poly(p-phenylene benzobisoxazole) fibers: Multifunctional interface for photothermal self-healing

Science.gov (United States)

Shao, Qing; Hu, Zhen; Xu, Xirong; Yu, Long; Zhang, Dayu; Huang, Yudong

2018-05-01

The composites with interfacial self-healing ability are smart and promising materials in the future. Although some approaches have been used to heal the micro-cracks in composite materials, it is still a great challenge to develop a versatile strategy to fabricate multifunctional interface for self-healing. Here, boron nitride nanosheets (BN) are immobilized onto PBO fibers by facile polydopamine (PDA) chemistry. Benefiting from the photothermal effect of BN-PDA, the obtained surface layer displays interfacial self-healing properties under Xenon light irradiation.

The resilient hybrid fiber sensor network with self-healing function

Energy Technology Data Exchange (ETDEWEB)

Xu, Shibo, E-mail: Shibo-Xu@tju.edu.cn; Liu, Tiegen; Ge, Chunfeng; Chen, Qinnan; Zhang, Hongxia [College of Precision Instrument and Opto-electronics Engineering, Tianjin University, Tianjin 300072 (China); Key Laboratory of Opto-electronics Information Technology (Tianjin University), Ministry of Education, Tianjin 300072 (China)

2015-03-15

This paper presents a novel resilient fiber sensor network (FSN) with multi-ring architecture, which could interconnect various kinds of fiber sensors responsible for more than one measurands. We explain how the intelligent control system provides sensors with self-healing function meanwhile sensors are working properly, besides each fiber in FSN is under real-time monitoring. We explain the software process and emergency mechanism to respond failures or other circumstances. To improve the efficiency in the use of limited spectrum resources in some situations, we have two different structures to distribute the light sources rationally. Then, we propose a hybrid sensor working in FSN which is a combination of a distributed sensor and a FBG (Fiber Bragg Grating) array fused in a common fiber sensing temperature and vibrations simultaneously with neglectable crosstalk to each other. By making a failure to a working fiber in experiment, the feasibility and effectiveness of the network with a hybrid sensor has been demonstrated, hybrid sensors could not only work as designed but also survive from destructive failures with the help of resilient network and smart and quick self-healing actions. The network has improved the viability of the fiber sensors and diversity of measurands.

The resilient hybrid fiber sensor network with self-healing function

Science.gov (United States)

Xu, Shibo; Liu, Tiegen; Ge, Chunfeng; Chen, Qinnan; Zhang, Hongxia

2015-03-01

This paper presents a novel resilient fiber sensor network (FSN) with multi-ring architecture, which could interconnect various kinds of fiber sensors responsible for more than one measurands. We explain how the intelligent control system provides sensors with self-healing function meanwhile sensors are working properly, besides each fiber in FSN is under real-time monitoring. We explain the software process and emergency mechanism to respond failures or other circumstances. To improve the efficiency in the use of limited spectrum resources in some situations, we have two different structures to distribute the light sources rationally. Then, we propose a hybrid sensor working in FSN which is a combination of a distributed sensor and a FBG (Fiber Bragg Grating) array fused in a common fiber sensing temperature and vibrations simultaneously with neglectable crosstalk to each other. By making a failure to a working fiber in experiment, the feasibility and effectiveness of the network with a hybrid sensor has been demonstrated, hybrid sensors could not only work as designed but also survive from destructive failures with the help of resilient network and smart and quick self-healing actions. The network has improved the viability of the fiber sensors and diversity of measurands.

The resilient hybrid fiber sensor network with self-healing function

International Nuclear Information System (INIS)

Xu, Shibo; Liu, Tiegen; Ge, Chunfeng; Chen, Qinnan; Zhang, Hongxia

2015-01-01

This paper presents a novel resilient fiber sensor network (FSN) with multi-ring architecture, which could interconnect various kinds of fiber sensors responsible for more than one measurands. We explain how the intelligent control system provides sensors with self-healing function meanwhile sensors are working properly, besides each fiber in FSN is under real-time monitoring. We explain the software process and emergency mechanism to respond failures or other circumstances. To improve the efficiency in the use of limited spectrum resources in some situations, we have two different structures to distribute the light sources rationally. Then, we propose a hybrid sensor working in FSN which is a combination of a distributed sensor and a FBG (Fiber Bragg Grating) array fused in a common fiber sensing temperature and vibrations simultaneously with neglectable crosstalk to each other. By making a failure to a working fiber in experiment, the feasibility and effectiveness of the network with a hybrid sensor has been demonstrated, hybrid sensors could not only work as designed but also survive from destructive failures with the help of resilient network and smart and quick self-healing actions. The network has improved the viability of the fiber sensors and diversity of measurands

Design and Analysis of Self-Healing Tree-Based Hybrid Spectral Amplitude Coding OCDMA System

Directory of Open Access Journals (Sweden)

Waqas A. Imtiaz

2017-01-01

Full Text Available This paper presents an efficient tree-based hybrid spectral amplitude coding optical code division multiple access (SAC-OCDMA system that is able to provide high capacity transmission along with fault detection and restoration throughout the passive optical network (PON. Enhanced multidiagonal (EMD code is adapted to elevate system’s performance, which negates multiple access interference and associated phase induced intensity noise through efficient two-matrix structure. Moreover, system connection availability is enhanced through an efficient protection architecture with tree and star-ring topology at the feeder and distribution level, respectively. The proposed hybrid architecture aims to provide seamless transmission of information at minimum cost. Mathematical model based on Gaussian approximation is developed to analyze performance of the proposed setup, followed by simulation analysis for validation. It is observed that the proposed system supports 64 subscribers, operating at the data rates of 2.5 Gbps and above. Moreover, survivability and cost analysis in comparison with existing schemes show that the proposed tree-based hybrid SAC-OCDMA system provides the required redundancy at minimum cost of infrastructure and operation.

Tritium permeation barrier based on self-healing composite materials

International Nuclear Information System (INIS)

Gao Jifeng; Zhang Dan; Suo Jinping

2010-01-01

Pores and cracks in ceramic coatings is one of the most important problems to be solved for the thermally sprayed tritium permeation barriers (TPBs) in fusion reactor. In this work, we developed a self-healing composite coating to address this problem. The coating composed of TiC + mixture(TiC/Al 2 O 3 ) + Al 2 O 3 was deposited on martensitic steels by means of atmospheric plasma spraying (APS). Before and after heat treatment, the morphology and phase of the coating were comparatively investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). In the experiment, NiAl + Al 2 O 3 , mixture(TiC/Al 2 O 3 ) + Al 2 O 3 and NiAl + TiC + mixture(TiC/Al 2 O 3 ) + Al 2 O 3 films were also fabricated and studied, respectively. The results showed that the TiC + mixture(TiC/Al 2 O 3 ) + Al 2 O 3 coating exhibited the best self-healing ability and good thermal shock resistance among the four samples after heat treatment under normal atmosphere. The SEM images analyzed by Image Pro software indicated that the porosity of the TiC + mixture(TiC/Al 2 O 3 ) + Al 2 O 3 coating decreased more than 90% in comparison with the sample before heat treatment. This self-healing coating made by thermal spraying might be a good candidate for tritium permeation barrier in fusion reactors.

Design, implementation, and demographic differences of HEAL: a self-report health care leadership instrument.

Science.gov (United States)

Murphy, Kelly R; McManigle, John E; Wildman-Tobriner, Benjamin M; Little Jones, Amy; Dekker, Travis J; Little, Barrett A; Doty, Joseph P; Taylor, Dean C

2016-01-01

The medical community has recognized the importance of leadership skills among its members. While numerous leadership assessment tools exist at present, few are specifically tailored to the unique health care environment. The study team designed a 24-item survey (Healthcare Evaluation & Assessment of Leadership [HEAL]) to measure leadership competency based on the core competencies and core principles of the Duke Healthcare Leadership Model. A novel digital platform was created for use on handheld devices to facilitate its distribution and completion. This pilot phase involved 126 health care professionals self-assessing their leadership abilities. The study aimed to determine both the content validity of the survey and the feasibility of its implementation and use. The digital platform for survey implementation was easy to complete, and there were no technical problems with survey use or data collection. With regard to reliability, initial survey results revealed that each core leadership tenet met or exceeded the reliability cutoff of 0.7. In self-assessment of leadership, women scored themselves higher than men in questions related to patient centeredness ( P =0.016). When stratified by age, younger providers rated themselves lower with regard to emotional intelligence and integrity. There were no differences in self-assessment when stratified by medical specialty. While only a pilot study, initial data suggest that HEAL is a reliable and easy-to-administer survey for health care leadership assessment. Differences in responses by sex and age with respect to patient centeredness, integrity, and emotional intelligence raise questions about how providers view themselves amid complex medical teams. As the survey is refined and further administered, HEAL will be used not only as a self-assessment tool but also in "360" evaluation formats.

Tough Self-Healing Elastomers by Molecular Enforced Integration of Covalent and Reversible Networks.

Science.gov (United States)

Wu, Jinrong; Cai, Li-Heng; Weitz, David A

2017-10-01

Self-healing polymers crosslinked by solely reversible bonds are intrinsically weaker than common covalently crosslinked networks. Introducing covalent crosslinks into a reversible network would improve mechanical strength. It is challenging, however, to apply this concept to "dry" elastomers, largely because reversible crosslinks such as hydrogen bonds are often polar motifs, whereas covalent crosslinks are nonpolar motifs. These two types of bonds are intrinsically immiscible without cosolvents. Here, we design and fabricate a hybrid polymer network by crosslinking randomly branched polymers carrying motifs that can form both reversible hydrogen bonds and permanent covalent crosslinks. The randomly branched polymer links such two types of bonds and forces them to mix on the molecular level without cosolvents. This enables a hybrid "dry" elastomer that is very tough with fracture energy 13500 Jm -2 comparable to that of natural rubber. Moreover, the elastomer can self-heal at room temperature with a recovered tensile strength 4 MPa, which is 30% of its original value, yet comparable to the pristine strength of existing self-healing polymers. The concept of forcing covalent and reversible bonds to mix at molecular scale to create a homogenous network is quite general and should enable development of tough, self-healing polymers of practical usage. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-healing effect of the protective inhibitor-containing coatings on Mg alloys

Science.gov (United States)

Gnedenkov, A. S.; Sinebryukhov, S. L.; Mashtalyar, D. V.; Gnedenkov, S. V.

2017-09-01

The method of self-healing coating formation on the surface of magnesium alloys on the base of plasma electrolytic oxidation (PEO) with subsequent impregnation of the obtained layer with inhibitor has been suggested. The protective and electrochemical properties of such coatings have been described. Localised Scanning Electrochemical Methods were used for determining the kinetics and mechanism of the self-healing process. The treatment with the solution containing inhibitor enables us to increase the protective properties of the PEO-coating in 30 times in the corrosion-active environment.

Self-healing of mechanically-loaded self consolidating concretes with high volumes of fly ash

Energy Technology Data Exchange (ETDEWEB)

Mustafa Sahmaran; Suleyman B. Keskin; Gozde Ozerkan; Ismail O. Yaman [University of Gaziantep, Gaziantep (Turkey). Department of Civil Engineering

2008-11-15

This article discusses the effects of self-healing on self consolidating concretes incorporating high volumes of fly ash (HVFA-SCC) when subjected to continuous water exposure. For this purpose, self consolidating concretes with fly ash replacement ratios of 0%, 35%, and 55% were prepared having a constant water-cementitious material ratio of 0.35. A uniaxial compression load was applied to generate microcracks in concrete where cylindrical specimens were pre-loaded up to 70% and 90% of the ultimate compressive load determined at 28 days. Later, the extent of damage was determined as percentage of loss in mechanical properties and percentage of increase in permeation properties. After pre-loading, concrete specimens were stored in water for a month and the mechanical and permeation properties are monitored at every two weeks. It was observed that HVFA-SCC mixtures initially lost 27% of their strength when pre-loaded up to 90% of their ultimate strength, and after 30 days of water curing that reduction was only 7%, indicating a substantial healing. On the other hand, for SCC specimens without fly ash that were pre-loaded to the same level, the loss in strength was initially 19%, and after a month of moist curing it was only 13%. Similar observations were also made on the permeation properties with greater effects. As the HVFA-SCCs studied have an important amount of unhydrated fly ash available in their microstructure, these observations are attributed to the self-healing of the pre-existing cracks, mainly by hydration of anhydrous fly ash particles on the crack surfaces.

Utilization of Self-Healing Materials in Thermal Protection System Applications

Data.gov (United States)

National Aeronautics and Space Administration — The proposed project is the Utilization of Self-Healing Materials for Thermal Protection System (TPS) Applications. Currently, the technology for repairing TPS from...

Studying the Combination Effect of Additives and Micro Steel Fibers on Cracks of Self-Healing Concrete

Directory of Open Access Journals (Sweden)

Muhannad Hussien Muhsin

2017-01-01

Full Text Available In this study, the effect of the combination of micro steel fibers and additives (calcium hydroxide and sodium carbonate on the size of cracks formation and healing them were investigated. This study aims to apply the use of self-healing phenomenon to repair cracks and to enhance the service life of the concrete structures. Micro steel fibers straight type were used in this research with 0.2% and 0.4% by volume of concrete. A weight of 20 and 30 kg/m3 of Ca(OH2 and 2 and 3 kg/m3 of Na2CO3 were used as a partial cement replacement. The results confirm that the concrete cracks were significantly self-healed up to 30 days re-curing. Cracks width up to 0.2 mm were completely self-healed after re-curing for 90 days by using the combination of micro steel fiber of 0.4% by volume of concrete and 25 kg/m3 of Ca(OH2 and 2.5 kg/m3 of Na2CO3 as a partial replacement of cement. Products of Self-healing are observed by Scanning Electron Microscopy (SEM with Energy Dispersive X-Ray Analysis (EDX. It was found that self-healing occurred mainly due to precipitation of calcium carbonate.

A Social Potential Fields Approach for Self-Deployment and Self-Healing in Hierarchical Mobile Wireless Sensor Networks.

Science.gov (United States)

González-Parada, Eva; Cano-García, Jose; Aguilera, Francisco; Sandoval, Francisco; Urdiales, Cristina

2017-01-09

Autonomous mobile nodes in mobile wireless sensor networks (MWSN) allow self-deployment and self-healing. In both cases, the goals are: (i) to achieve adequate coverage; and (ii) to extend network life. In dynamic environments, nodes may use reactive algorithms so that each node locally decides when and where to move. This paper presents a behavior-based deployment and self-healing algorithm based on the social potential fields algorithm. In the proposed algorithm, nodes are attached to low cost robots to autonomously navigate in the coverage area. The proposed algorithm has been tested in environments with and without obstacles. Our study also analyzes the differences between non-hierarchical and hierarchical routing configurations in terms of network life and coverage.

Interaction between microcapsules and cementitious matrix after cracking in a self-healing system

NARCIS (Netherlands)

Wang, X.; Xing, F.; Zhang, M.; Han, N.; Qian, Z.

2013-01-01

A new type of self-healing cementitious composites by using organic microcapsules is designed in Guangdong Key Laboratory of Durability for Coastal Civil Engineering, Shenzhen University. For the organic microcapsules, the shell material is urea formoldehyde (UF), and the core healing agent is

An Efficient Construction of Self-Dual Codes

OpenAIRE

Lee, Yoonjin; Kim, Jon-Lark

2012-01-01

We complete the building-up construction for self-dual codes by resolving the open cases over $GF(q)$ with $q \\equiv 3 \\pmod 4$, and over $\\Z_{p^m}$ and Galois rings $\\GR(p^m,r)$ with an odd prime $p$ satisfying $p \\equiv 3 \\pmod 4$ with $r$ odd. We also extend the building-up construction for self-dual codes to finite chain rings. Our building-up construction produces many new interesting self-dual codes. In particular, we construct 945 new extremal self-dual ternary $[32,16,9]$ codes, each ...

Biomimetic Self-Healing

Science.gov (United States)

2015-07-21

methyl-2-pyrrolidone (NMP), dimethylacetamide (DMA), dimethylformamide (DMF), and dimethylsulfoxide ( DMSO ) displayed the best results; unfortunately...Both techniques demand the production of a stable emulsion, using solvents that do not react with the healing substances. If water is used (and it...highly cross-linked UF polymer. Healing chemicals, solvents , surfactants, and emulsifiers are not shown. Figure 6. Synthesis of PU capsules

PENGARUH EFEKTIVITAS TERAPI SELF HEALING MENGGUNAKAN ENERGI REIKI TERHADAP KECEMASAN MENGHADAPI UJIAN SKRIPSI

Directory of Open Access Journals (Sweden)

Budiman Bahrien

2017-06-01

Full Text Available The educational process can become a source of stressor and anxiety, especially in the final stage of a college education (thesis exam for students. 5 of 15 College student Health Sciences Muhammadiyah Palembang experienced acute anxiety. In addition, 19 of the 67 students in STIKes Muhammadiyah who undergo remedial thesis examination have other physical complaints. Self healing using reiki energy can be utilized to reduce the anxiety state. This study investigates the effect of self healing reiki energy on anxiety. A quasi experimental design was used with the sample of forty respondents (20=intervention, 20=control group. One Way Anova was used to test the hypothesis. The results showed that there was a significant difference of the mean score of anxiety between the intervention and the control group during the post-test. Thus, treatment of self healing with Reiki energy is quite effective in reducing anxiety levels.

Understanding the molecular mechanisms involved in the interfacial self-healing of supramolecular rubbers

NARCIS (Netherlands)

Bose, R.K.; Garcia Espallargas, S.J.; Van der Zwaag, S.

2013-01-01

Supramolecular rubbers based on 2-aminoethylimidazolidone and fatty acids with epoxy crosslinks have been shown to self-heal via multiple hydrogen bonding sites. In this work, several tools are used to investigate the molecular mechanisms taking place at the interface to understand cohesive healing

Tritium permeation barrier based on self-healing composite materials

Energy Technology Data Exchange (ETDEWEB)

Gao Jifeng; Zhang Dan [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Suo Jinping, E-mail: jpsuo@yahoo.com.cn [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2010-12-15

Pores and cracks in ceramic coatings is one of the most important problems to be solved for the thermally sprayed tritium permeation barriers (TPBs) in fusion reactor. In this work, we developed a self-healing composite coating to address this problem. The coating composed of TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} was deposited on martensitic steels by means of atmospheric plasma spraying (APS). Before and after heat treatment, the morphology and phase of the coating were comparatively investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). In the experiment, NiAl + Al{sub 2}O{sub 3}, mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} and NiAl + TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} films were also fabricated and studied, respectively. The results showed that the TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} coating exhibited the best self-healing ability and good thermal shock resistance among the four samples after heat treatment under normal atmosphere. The SEM images analyzed by Image Pro software indicated that the porosity of the TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} coating decreased more than 90% in comparison with the sample before heat treatment. This self-healing coating made by thermal spraying might be a good candidate for tritium permeation barrier in fusion reactors.

A Social Potential Fields Approach for Self-Deployment and Self-Healing in Hierarchical Mobile Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Eva González-Parada

2017-01-01

Full Text Available Autonomous mobile nodes in mobile wireless sensor networks (MWSN allow self-deployment and self-healing. In both cases, the goals are: (i to achieve adequate coverage; and (ii to extend network life. In dynamic environments, nodes may use reactive algorithms so that each node locally decides when and where to move. This paper presents a behavior-based deployment and self-healing algorithm based on the social potential fields algorithm. In the proposed algorithm, nodes are attached to low cost robots to autonomously navigate in the coverage area. The proposed algorithm has been tested in environments with and without obstacles. Our study also analyzes the differences between non-hierarchical and hierarchical routing configurations in terms of network life and coverage.

Unfinished dreams: community healing and the reality of aboriginal self-government

National Research Council Canada - National Science Library

Warry, Wayne

1998-01-01

... of community development and cultural revitalization that are essential precursors to self-government. Warry's notion of 'community healing' involves efforts to rebuild the human foundations for self-governing Aboriginal societies. The book analyses key areas such as health care and the judicial and political systems where Aboriginal peoples ...

Reusable self-healing hydrogels realized via in situ polymerization.

Science.gov (United States)

Vivek, Balachandran; Prasad, Edamana

2015-04-09

In this work, a self-healing hydrogel has been prepared using in situ polymerization of acrylic acid and acrylamide in the presence of glycogen. The hydrogel was characterized using NMR, SEM, FT-IR, rheology, and dynamic light scattering (DLS) studies. The developed hydrogel exhibits self-healing properties at neutral pH, high swelling ability, high elasticity, and excellent mechanical strength. The hydrogel exhibits modulus values (G', G″) as high as 10(6) Pa and shows an exceptionally high degree of swelling ratio (∼3.5 × 10(3)). Further, the polymer based hydrogel adsorbs toxic metal ions (Cd(2+), Pb(2+), and Hg(2+)) and organic dyes (methylene blue and methyl orange) from contaminated water with remarkable efficiency (90-98%). The mechanistic analysis indicated the presence of pseudo-second-order reaction kinetics. The reusability of the hydrogel has been demonstrated by repeating the adsorption-desorption process over five cycles with identical results in the adsorption efficiency.

Intelligent saline enabled self-healing of multilayer coatings and its optimization to achieve redox catalytically provoked anti-corrosion ability

Energy Technology Data Exchange (ETDEWEB)

Syed, Junaid Ali; Tang, Shaochun; Meng, Xiangkang, E-mail: mengxk@nju.edu.cn

2016-10-15

Highlights: • Multilayer coatings were prepared with good self-healing and anti-corrosion ability. • The lifespan of SS is much improved and it is stable even after 120 h in 3.5% NaCl. • Multilayer structure with redox catalytic and self-healing ability leads to high P{sub e}. • Saline-triggered self-healing and anti-corrosion mechanisms were envisaged. - Abstract: To obtain a coating with both self-healing and redox catalytic ability to protect a metal substrate from corrosion under aggressive environment is strongly desired. Herein, we report the design and fabrication of intelligent polyaniline-polyacrylic acid/polyethyleneimine (PANI-PAA/PEI) multilayer composite coatings by spin assembly. The main influencing factors, including solution concentration (c) and disk rotating speed (ω) were studied in order to gain excellent performance. The resulting multilayer coatings with thickness in a range from 0.47 to 2.94 μm can heal severe structural damages and sustain a superior anti-corrosive performance for 120 h in 3.5% NaCl. The PANI-PAA layer enhances the anti-corrosion property and PEI layer contributes to the self-healing ability as well as their multilayer combination strengthens them. The improved self-healing ability is attributed to the rearrangement and reversible non-covalent interactions of the PANI-PAA and PEI layers that facilitates electrostatic repairing.

Simulation of the self-healing of dolomitic lime mortar

NARCIS (Netherlands)

Lubelli, B.; Nijland, T.G.; Hees, R.P.J. van

2012-01-01

A test procedure was set up to reproduce laboratory self-healing on lime-based (both pure calcium and magnesium-calcium) mortar specimens. After a few months of testing, during which time the specimens were submitted to wet-dry cycles, thin sections of the specimens were prepared and observed using

Monitoring the restoration of interfacial contact for self healing thermal interface materials for LED and microelectronic applications

NARCIS (Netherlands)

Lafont, U.L.; Van Zeijl, H.W.; Van der Zwaag, S.

2013-01-01

While conventional self healing materials focus on the restoration of mechanical properties, newer generations of self healing materials focus on the restoration of other functional (i.e. non-mechanical) properties. Thermal conductivity is an example of an important functional property of a Thermal

Design, implementation, and demographic differences of HEAL: a self-report health care leadership instrument

Directory of Open Access Journals (Sweden)

Murphy KR

2016-10-01

Full Text Available Kelly R Murphy, John E McManigle, Benjamin M Wildman-Tobriner, Amy Little Jones, Travis J Dekker, Barrett A Little, Joseph P Doty, Dean C Taylor Duke Healthcare Leadership Program, Duke University School of Medicine, Durham, NC, USA Abstract: The medical community has recognized the importance of leadership skills among its members. While numerous leadership assessment tools exist at present, few are specifically tailored to the unique health care environment. The study team designed a 24-item survey (Healthcare Evaluation & Assessment of Leadership [HEAL] to measure leadership competency based on the core competencies and core principles of the Duke Healthcare Leadership Model. A novel digital platform was created for use on handheld devices to facilitate its distribution and completion. This pilot phase involved 126 health care professionals self-assessing their leadership abilities. The study aimed to determine both the content validity of the survey and the feasibility of its implementation and use. The digital platform for survey implementation was easy to complete, and there were no technical problems with survey use or data collection. With regard to reliability, initial survey results revealed that each core leadership tenet met or exceeded the reliability cutoff of 0.7. In self-assessment of leadership, women scored themselves higher than men in questions related to patient centeredness (P=0.016. When stratified by age, younger providers rated themselves lower with regard to emotional intelligence and integrity. There were no differences in self-assessment when stratified by medical specialty. While only a pilot study, initial data suggest that HEAL is a reliable and easy-to-administer survey for health care leadership assessment. Differences in responses by sex and age with respect to patient centeredness, integrity, and emotional intelligence raise questions about how providers view themselves amid complex medical teams. As the

Multiple self-healing squamous epithelioma er en arvelig tilstand med selvhelende hudkræft

DEFF Research Database (Denmark)

Broesby-Olsen, Sigurd; Frandsen, Stine Krog; Thomassen, Mads

2012-01-01

Multiple self-healing squamous epithelioma - Ferguson-Smith disease (MSSE) is an autosomal dominant inherited disease with multiple, recurrent, histologically malignant tumours that undergo spontaneous regression. The gene for MSSE has recently been identified as the transforming growth factor-be......-beta receptor 1 (TGFBR1). Although rare, MSSE constitutes an important model of tumour-biology research. The discovery of the genetic background for MSSE paves the way for further elucidating the mechanisms involved in this peculiar self-healing cancer syndrome....

Intrinsic self-healing thermoset through covalent and hydrogen bonding interactions

NARCIS (Netherlands)

Araya-Hermosilla, R.; Lima, G. M. R.; Raffa, P.; Fortunato, G.; Pucci, A.; Flores, Mario E.; Moreno-Villoslada, I.; Broekhuis, A. A.; Picchioni, F.

The intrinsic self-healing ability of polyketone (PK) chemically modified into furan and/or OH groups containing derivatives is presented. Polymers bearing different ratios of both functional groups were cross-linked via furan/bis-maleimide (Diels-Alder adducts) and hydrogen bonding interactions

Development of electrically insulating self-healing coatings in vanadium alloys for lithium fusion reactor

International Nuclear Information System (INIS)

1999-01-01

Problems on electrically insulating self-healing coatings (SHC) on vanadium alloys for lithium fusion reactor systems are considered. In particular, the SHC stability and radiation resistance in lithium and effect of magnetic field on the efficiency of the TNR lithium systems are studied. New technological methods for application of self-healing coatings and study on their properties are developed. The vanadium-lithium materials testing in pile loops for solution of the above problems under conditions of the lithium TNR is described [ru

Mechanical Characterization of High-Performance Steel-Fiber Reinforced Cement Composites with Self-Healing Effect

Science.gov (United States)

Kim, Dong Joo; Kang, Seok Hee; Ahn, Tae-Ho

2014-01-01

The crack self-healing behavior of high-performance steel-fiber reinforced cement composites (HPSFRCs) was investigated. High-strength deformed steel fibers were employed in a high strength mortar with very fine silica sand to decreasing the crack width by generating higher interfacial bond strength. The width of micro-cracks, strongly affected by the type of fiber and sand, clearly produced the effects on the self-healing behavior. The use of fine silica sand in HPSFRCs with high strength deformed steel fibers successfully led to rapid healing owing to very fine cracks with width less than 20 μm. The use of very fine silica sand instead of normal sand produced 17%–19% higher tensile strength and 51%–58% smaller width of micro-cracks. PMID:28788471

Autonomous distributed self-organizing and self-healing hardware architecture - The eDNA concept

DEFF Research Database (Denmark)

Boesen, Michael Reibel; Madsen, Jan; Keymeulen, Didier

2011-01-01

This paper presents the current state of the autonomous distributed self-organizing and self-healing electronic DNA (eDNA) hardware architecture (patent pending). In its current prototype state, the eDNA architecture is capable of responding to multiple injected faults by autonomously reconfiguring...... itself to accommodate the fault and keep the application running. This paper will also disclose advanced features currently available in the simulation model only. These features are future work and will soon be implemented in hardware. Finally we will describe step-by-step how an application...

Healing Arts Radiation Protection Act

International Nuclear Information System (INIS)

1984-07-01

The Healing Arts Radiation Protection Act is concerned with regulating the registration, installation, operation, inspection and safety of X-ray machines. The Act provides for the establishment of the Healing Arts Radiation Protection Commission which is responsible for reporting on all the above matters to the Ontario Minister of Health. In addition the board is responsible for the continuing development of an X-ray safety code and for the submission of an annual report of their activities to the minister

Towards an understanding of thermally activated self-healing of an ionomer system during ballistic penetration

International Nuclear Information System (INIS)

Varley, Russell J.; Zwaag, Sybrand van der

2008-01-01

The self-healing phenomenon exhibited by the ionomer known as Surlyn 8940 (DuPont), a partially neutralized poly(ethylene-co-methacrylic acid) random co-polymer, during high-energy impact has been investigated here according to three separate strategies. The first consisted of a post-mortem scanning electron microscopy examination of impact surfaces of actual ballistic impacts for a range of bullets with different shapes, sizes and velocities. A complex range of competing and/or complementary processes based upon elastic and viscous responses was observed. The elastic response to impact provides for a polymer rebound or shape memory effect, while the viscous response provides for the final sealing of the cavity and is dependent upon the level of thermal frictional forces transferred during impact. The balance of these influences determines healing, and is shown to be altered by the size and shape of the bullet or indeed by the polymer morphology itself. The second strategy investigated the healing mechanism using a method that mimics the elastic response to impact in a controlled environment. This work highlighted the importance of the ionic clusters present in the ionomer and the gradient of viscoelastic properties formed at varying distances from the impact zone particularly when compared to non-ionic polymers. The repeatability of elastic healing was demonstrated, and reinforced the notion that healing arose from the inherent polymer structure of the ionomer. The third strategy investigated the role of the viscous response during impact and found that increased molecular mobility in the melt was critical to achieving optimal healing, although again the ionic clusters were found to be critical to maintaining sufficient structural integrity and preventing excess viscous flow

Formation and 'self-healing' of magnetic islands in finite-β Helias equilibria

International Nuclear Information System (INIS)

Hayashi, T.; Sato, T.; Merkel, P.; Nuehrenberg, J.; Schwenn, U.

1994-01-01

The behaviour of finite-pressure-induced magnetic islands is numerically analyzed for three-dimensional magnetohydrodynamic equilibria of the Helias configuration by using a three-dimensional equilibrium code. It is found that an island chain is generated on the 5/6 rational surface, when such a surface appears in the plasma region of the finite-β equilibrium. The island chain, however, is not so dangerous as to destroy the plasma confinement even if it appears in a vanishingly small shear region. Thus, a high β equilibrium with clear magnetic surfaces can be realized. Moreover, it is definitely confirmed that the finite pressure effect sometimes exhibits an unexpectedly good aspect, namely, that the vacuum islands are removed as β increases, which can be called 'self-healing' of islands. This property can be explained by the numerically discovered fact that the phases of islands induced by the finite-pressure effect are always locked in the same phase regardless of β. (author)

Synthesis of durable microcapsules for self-healing anticorrosive coatings: A comparison of selected methods

DEFF Research Database (Denmark)

Nesterova, Tatyana; Dam-Johansen, Kim; Kiil, Søren

2011-01-01

-based anticorrosive coatings, based on incorporation of microcapsules, filled with reactive agents, into the coating matrix, is investigated. Upon small damages to the coating, the reagents are released from the capsules and react, thereby forming a cross-linked network, which heals the crack. However......Self-healing materials have the ability to ‘repair’ themselves upon exposure to an external stimulus. In the field of coatings, extensive laboratory research has been conducted on these so-called smart materials in the last decade. In the present work, a self-healing concept for epoxy......, for the concept to work, microcapsules have to be strong enough to remain intact during storage and coating formulation and application. Furthermore, the capsules must remain stable for many years in the dry coating. Laboratory experiments, using four out of several encapsulation methods available...

Skin-Inspired Multifunctional Autonomic-Intrinsic Conductive Self-Healing Hydrogels with Pressure Sensitivity, Stretchability, and 3D Printability.

Science.gov (United States)

Darabi, Mohammad Ali; Khosrozadeh, Ali; Mbeleck, Rene; Liu, Yuqing; Chang, Qiang; Jiang, Junzi; Cai, Jun; Wang, Quan; Luo, Gaoxing; Xing, Malcolm

2017-08-01

The advent of conductive self-healing (CSH) hydrogels, a class of novel materials mimicking human skin, may change the trajectory of the industrial process because of their potential applications in soft robots, biomimetic prostheses, and health-monitoring systems. Here, the development of a mechanically and electrically self-healing hydrogel based on physically and chemically cross-linked networks is reported. The autonomous intrinsic self-healing of the hydrogel is attained through dynamic ionic interactions between carboxylic groups of poly(acrylic acid) and ferric ions. A covalent cross-linking is used to support the mechanical structure of the hydrogel. Establishing a fair balance between the chemical and physical cross-linking networks together with the conductive nanostructure of polypyrrole networks leads to a double network hydrogel with bulk conductivity, mechanical and electrical self-healing properties (100% mechanical recovery in 2 min), ultrastretchability (1500%), and pressure sensitivity. The practical potential of CSH hydrogels is further revealed by their application in human motion detection and their 3D-printing performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Overcoming the Instability of Nanoparticle-Based Catalyst Films in Alkaline Electrolyzers by using Self-Assembling and Self-Healing Films

NARCIS (Netherlands)

Barwe, Stefan; Masa, Justus; Andronescu, Corina; Mei, Bastian; Schuhmann, Wolfgang; Ventosa, Edgar

2017-01-01

Engineering stable electrodes using highly active catalyst nanopowders for electrochemical water splitting remains a challenge. We report an innovative and general approach for attaining highly stable catalyst films with self-healing capability based on the in situ self-assembly of catalyst

Amine-modified magnetic iron oxide nanoparticle as a promising carrier for application in bio self-healing concrete.

Science.gov (United States)

Seifan, Mostafa; Ebrahiminezhad, Alireza; Ghasemi, Younes; Samani, Ali Khajeh; Berenjian, Aydin

2018-01-01

Self-healing mechanisms are a promising solution to address the concrete cracking issue. Among the investigated self-healing strategies, the biotechnological approach is distinguished itself by inducing the most compatible material with concrete composition. In this method, the potent bacteria and nutrients are incorporated into the concrete matrix. Once cracking occurs, the bacteria will be activated, and the induced CaCO 3 crystals will seal the concrete cracks. However, the effectiveness of a bio self-healing concrete strictly depends on the viability of bacteria. Therefore, it is required to protect the bacteria from the resulted shear forces caused by mixing and drying shrinkage of concrete. Due to the positive effects on mechanical properties and the high compatibility of metallic nanoparticles with concrete composition, for the first time, we propose 3-aminopropyltriethoxy silane-coated iron oxide nanoparticles (APTES-coated IONs) as a biocompatible carrier for Bacillus species. This study was aimed to investigate the effect of APTES-coated IONs on the bacterial viability and CaCO 3 yield for future application in the concrete structures. The APTES-coated IONs were successfully synthesized and characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results show that the presence of 100 μg/mL APTES-coated IONs could increase the bacterial viability. It was also found that the CaCO 3 -specific yield was significantly affected in the presence of APTES-coated IONs. The highest CaCO 3 -specific yield was achieved when the cells were decorated with 50 μg/mL of APTES-coated IONs. This study provides new insights for the application of APTES-coated IONs in designing bio self-healing strategies.

Design of Self-Healing Supramolecular Rubbers by Introducing Ionic Cross-Links into Natural Rubber via a Controlled Vulcanization.

Science.gov (United States)

Xu, Chuanhui; Cao, Liming; Lin, Baofeng; Liang, Xingquan; Chen, Yukun

2016-07-13

Introducing ionic associations is one of the most effective approaches to realize a self-healing behavior for rubbers. However, most of commercial rubbers are nonpolar rubbers without now available functional groups to be converted into ionic groups. In this paper, our strategy was based on a controlled peroxide-induced vulcanization to generate massive ionic cross-links via polymerization of zinc dimethacrylate (ZDMA) in natural rubber (NR) and exploited it as a potential self-healable material. We controlled vulcanization process to retard the formation of covalent cross-link network, and successfully generated a reversible supramolecular network mainly constructed by ionic cross-links. Without the restriction of covalent cross-linkings, the NR chains in ionic supramolecular network had good flexibility and mobility. The nature that the ionic cross-links was easily reconstructed and rearranged facilitating the self-healing behavior, thereby enabling a fully cut sample to rejoin and retain to its original properties after a suitable self-healing process at ambient temperature. This study thus demonstrates a feasible approach to impart an ionic association induced self-healing function to commercial rubbers without ionic functional groups.

Development of Self-Healing Coatings Based on Linseed Oil as Autonomous Repairing Agent for Corrosion Resistance

Directory of Open Access Journals (Sweden)

Karan Thanawala

2014-11-01

Full Text Available In recent years corrosion-resistant self-healing coatings have witnessed strong growth and their successful laboratory design and synthesis categorises them in the family of smart/multi-functional materials. Among various approaches for achieving self-healing, microcapsule embedment through the material matrix is the main one for self-healing ability in coatings. The present work focuses on optimizing the process parameters for developing microcapsules by in-situ polymerization of linseed oil as core and urea-formaldehyde as shell material. Characteristics of these microcapsules with respect to change in processing parameters such as stirring rate and reaction time were studied by using optical microscopy (OM, scanning electron microscopy (SEM and Fourier transform infrared spectroscopy (FT-IR. The effectiveness of these microcapsules in coatings was characterized by studying their adhesion, performance, and mechanical properties.

Monitoring of Postoperative Bone Healing Using Smart Trauma-Fixation Device With Integrated Self-Powered Piezo-Floating-Gate Sensors.

Science.gov (United States)

Borchani, Wassim; Aono, Kenji; Lajnef, Nizar; Chakrabartty, Shantanu

2016-07-01

Achieving better surgical outcomes in cases of traumatic bone fractures requires postoperative monitoring of changes in the growth and mechanical properties of the tissue and bones during the healing process. While current in-vivo imaging techniques can provide a snapshot of the extent of bone growth, it is unable to provide a history of the healing process, which is important if any corrective surgery is required. Monitoring the time evolution of in-vivo mechanical loads using existing technology is a challenge due to the need for continuous power while maintaining patient mobility and comfort. This paper investigates the feasibility of self-powered monitoring of the bone-healing process using our previously reported piezo-floating-gate (PFG) sensors. The sensors are directly integrated with a fixation device and operate by harvesting energy from microscale strain variations in the fixation structure. We show that the sensors can record and store the statistics of the strain evolution during the healing process for offline retrieval and analysis. Additionally, we present measurement results using a biomechanical phantom comprising of a femur fracture fixation plate; bone healing is emulated by inserting different materials, with gradually increasing elastic moduli, inside a fracture gap. The PFG sensor can effectively sense, compute, and record continuously evolving statistics of mechanical loading over a typical healing period of a bone, and the statistics could be used to differentiate between different bone-healing conditions. The proposed sensor presents a reliable objective technique to assess bone-healing progress and help decide on the removal time of the fixation device.

Self-healing systems and wireless networks management

CERN Document Server

Chaudhry, Junaid Ahsenali

2013-01-01

Do you believe in open-source development? Would you like to see your security system grow and learn by itself? Are you sick of paying for software license fees every year that produce little return on investment? And, would you prefer to invest in something you could sell later on to other IT security departments? If you answered yes to these questions, then this is the book for you.Addressing the issues of fault identification and classification, Self-Healing Systems and Wireless Networks Management presents a method for identifying and classifying faults using ca

The microstructure of self-healed PVA ECC under wet and dry cycles

Directory of Open Access Journals (Sweden)

Jia Huan Yu

2010-06-01

Full Text Available Self-healing of ECC (Engineered Cementitious Composites subjected to cyclic wetting and drying regimes is investigated in this paper. ECC structures subjected to outdoor environmental conditions such as wind and rain runoff can be simulated by accelerated test method of wetting and drying cycles. Uniaxial tensile tests of ECC M45 and ECC 2.8FA specimen are conducted respectively. It is found that crack width of ECC 2.8FA is around 10 μm with increased amount of fly ash, while the crack width of ECC M45 is around 100 μm. New insights about the microstructure and chemical composition analysis of ECC specimens initially cracked to 2% strain and then self-healed under wet-dry cycles are presented.

Thermally responsive polymer systems for self-healing, reversible adhesion and shape memory applications

Science.gov (United States)

Luo, Xiaofan

Responsive polymers are "smart" materials that are capable of performing prescribed, dynamic functions under an applied stimulus. In this dissertation, we explore several novel design strategies to develop thermally responsive polymers and polymer composites for self-healing, reversible adhesion and shape memory applications. In the first case described in Chapters 2 and 3, a thermally triggered self-healing material was prepared by blending a high-temperature epoxy resin with a thermoplastic polymer, poly(epsilon-caprolactone) (PCL). The initially miscible system undergoes polymerization induced phase separation (PIPS) during the curing of epoxy and yields a variety of compositionally dependent morphologies. At a particular PCL loading, the cured blend displays a "bricks-and-mortar" morphology in which epoxy exists as interconnected spheres ("bricks") within a continuous PCL matrix ("mortar"). A heat induced "bleeding" phenomenon was observed in the form of spontaneous wetting of all free surfaces by the molten PCL, and is attributed to the volumetric thermal expansion of PCL above its melting point in excess of epoxy brick expansion, which we term differential expansive bleeding (DEB). This DEB is capable of healing damage such as cracks. In controlled self-healing experiments, heating of a cracked specimen led to PCL bleeding from the bulk that yields a liquid layer bridging the crack gap. Upon cooling, a "scar" composed of PCL crystals was formed at the site of the crack, restoring a significant portion of mechanical strength. We further utilized DEB to enable strong and thermally-reversible adhesion of the material to itself and to metallic substrates, without any requirement for macroscopic softening or flow. After that, Chapters 4--6 present a novel composite strategy for the design and fabrication of shape memory polymer composites. The basic approach involves physically combining two or more functional components into an interpenetrating fiber

Damage detection monitoring applications in self-healing concrete structures using embedded piezoelectric transducers and recovery

International Nuclear Information System (INIS)

Karaiskos, G; Tsangouri, E; Aggelis, D G; Van Hemelrijck, D; Deraemaeker, A

2015-01-01

The ageing, operational and ambient loadings have a great impact in the operational and maintenance cost of concrete structures. Their service life prolongation is of utmost importance and this can be efficiently achieved by using reliable and low-cost monitoring and self-healing techniques. In the present study, the ultrasonic pulse velocity (UPV) method using embedded small-size and low-cost piezoelectric PZT (lead zirconate titanate) ceramic transducers in concrete with self-healing properties is implemented for monitoring not only the setting and hardening phases of concrete since casting time, but also for the detection of damage initiation, propagation and recovery of integrity after healing. A couple of small-scale notched unreinforced concrete beams are subjected to mode-I fracture through three-point bending tests. After a 24-hour healing agent curing period, the beams are reloaded using the same loading scenario. The results demonstrate the excellent performance of the proposed monitoring technique during the hydration, damage generation and recovery periods. (paper)

Advanced self-healing asphalt composites in the pavement performance field: mechanisms at the nano level and new repairing methodologies.

Science.gov (United States)

Agzenai, Yahya; Pozuelo, Javier; Sanz, Javier; Perez, Ignacio; Baselga, Juan

2015-01-01

In an effort to give a global view of this field of research, in this mini-review we highlight the most recent publications and patents focusing on modified asphalt pavements that contain certain reinforcing nanoparticles which impart desirable thermal, electrical and mechanical properties. In response to the increasing cost of asphalt binder and road maintenance, there is a need to look for alternative technologies and new asphalt composites, able to self-repair, for preserving and renewing the existing pavements. First, we will focus on the self-healing property of asphalt, the evidences that support that healing takes place immediately after the contact between the faces of a crack, and how the amount of healing can be measured in both the laboratory and the field. Next we review the hypothetical mechanisms of healing to understand the material behaviour and establish models to quantify the damage-healing process. Thereafter, we outline different technologies, nanotechnologies and methodologies used for self-healing paying particular attention to embedded micro-capsules, new nano-materials like carbon nanotubes and nano-fibres, ionomers, and microwave and induction heating processes.

New MDS or near MDS self-dual codes over finite fields

OpenAIRE

Tong, Hongxi; Wang, Xiaoqing

2016-01-01

The study of MDS self-dual codes has attracted lots of attention in recent years. There are many papers on determining existence of $q-$ary MDS self-dual codes for various lengths. There are not existence of $q-$ary MDS self-dual codes of some lengths, even these lengths $< q$. We generalize MDS Euclidean self-dual codes to near MDS Euclidean self-dual codes and near MDS isodual codes. And we obtain many new near MDS isodual codes from extended negacyclic duadic codes and we obtain many new M...

Conformation-Directed Formation of Self-Healing Diblock Copolypeptide Hydrogels via Polyion Complexation.

Science.gov (United States)

Sun, Yintao; Wollenberg, Alexander L; O'Shea, Timothy Mark; Cui, Yanxiang; Zhou, Z Hong; Sofroniew, Michael V; Deming, Timothy J

2017-10-25

Synthetic diblock copolypeptides were designed to incorporate oppositely charged ionic segments that form β-sheet-structured hydrogel assemblies via polyion complexation when mixed in aqueous media. The observed chain conformation directed assembly was found to be required for efficient hydrogel formation and provided distinct and useful properties to these hydrogels, including self-healing after deformation, microporous architecture, and stability against dilution in aqueous media. While many promising self-assembled materials have been prepared using disordered or liquid coacervate polyion complex (PIC) assemblies, the use of ordered chain conformations in PIC assemblies to direct formation of new supramolecular morphologies is unprecedented. The promising attributes and unique features of the β-sheet-structured PIC hydrogels described here highlight the potential of harnessing conformational order derived from PIC assembly to create new supramolecular materials.

Overcoming the Instability of Nanoparticle-Based Catalyst Films in Alkaline Electrolyzers by using Self-Assembling and Self-Healing Films.

Science.gov (United States)

Barwe, Stefan; Masa, Justus; Andronescu, Corina; Mei, Bastian; Schuhmann, Wolfgang; Ventosa, Edgar

2017-07-10

Engineering stable electrodes using highly active catalyst nanopowders for electrochemical water splitting remains a challenge. We report an innovative and general approach for attaining highly stable catalyst films with self-healing capability based on the in situ self-assembly of catalyst particles during electrolysis. The catalyst particles are added to the electrolyte forming a suspension that is pumped through the electrolyzer. Particles with negatively charged surfaces stick onto the anode, while particles with positively charged surfaces stick to the cathode. The self-assembled catalyst films have self-healing properties as long as sufficient catalyst particles are present in the electrolyte. The proof-of-concept was demonstrated in a non-zero gap alkaline electrolyzer using NiFe-LDH and Ni x B catalyst nanopowders for anode and cathode, respectively. Steady cell voltages were maintained for at least three weeks during continuous electrolysis at 50-100 mA cm -2 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multifunctional Shielding and Self-Healing HybridSil Smart Composites for Space, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — NanoSonic has developed revolutionary multifunctional, super lightweight, self-healing and radiation shielding carbon fiber reinforced polymer (CFRP) composites as a...

A critical appraisal of the potential of self healing polymeric coatings

NARCIS (Netherlands)

García, S.J.; Fischer, H.R.; Zwaag, S. van der

2011-01-01

Several approaches and concepts to self healing materials have appeared in the literature over the last years, all presenting advantages and disadvantages, but definitely showing the great potential of this new class of materials to increase the lifetime of structures and to decrease maintenance

Proceedings of the self-healing topical session of the IGSC Working Group on Measurement and Physical Understanding of Groundwater Flow through Argillaceous Media (Clay Club)

International Nuclear Information System (INIS)

2001-01-01

A Topical Session focused on the 'Evidence of, and Approaches to Self-Healing in Argillaceous Media' was organised in the framework to the 11. meeting of the Clay Club. It was held at Nancy in France on 16 May 2001 at the invitation of the French Organisation for Radioactive Waste Management (ANDRA). Twenty-six participants representing several national waste management organisations, regulatory authorities, geological surveys as well as academic community took part in the session. The Topical session was mainly aimed at exchanging information on: - The general point of view on self-healing from geomechanical and geochemical experts; - The approaches that are or will be followed by the various organisations in order to deal with self-healing. The geological settings covered in the presentations concerned the whole range of argillaceous media, from soft, plastic clays to indurated clay-stones, currently studied with respect to deep disposal of radioactive waste. The Topical Session showed the importance of a multidisciplinary approach to this topic. The presentations emphasised the interest of a state-of-the-art report on self-healing to provide a sound and disposal-dedicated scientific framework for subsequent studies related to this area

Effect of temperature on surface error and laser damage threshold for self-healing BK7 glass.

Science.gov (United States)

Wang, Chu; Wang, Hongxiang; Shen, Lu; Hou, Jing; Xu, Qiao; Wang, Jian; Chen, Xianhua; Liu, Zhichao

2018-03-20

Cracks caused during the lapping and polishing process can decrease the laser-induced damage threshold (LIDT) of the BK7 glass optical elements, which would shorten the lifetime and limit the output power of the high-energy laser system. When BK7 glass is heated under appropriate conditions, the surface cracks can exhibit a self-healing phenomenon. In this paper, based on thermodynamics and viscous fluid mechanics theory, the mechanisms of crack self-healing are explained. The heat-healing experiment was carried out, and the effect of water was analyzed. The multi-spatial-frequency analysis was used to investigate the effect of temperature on surface error for self-healing BK7 glass, and the lapped BK7 glass specimens before and after heat healing were detected by an interferometer and atomic force microscopy. The low-spatial-frequency error was analyzed by peak to valley and root mean square, the mid-spatial-frequency error was analyzed by power spectral density, and the high-spatial-frequency error was analyzed by surface roughness. The results showed that the optimal heating temperature for BK7 was 450°C, and when the heating temperature was higher than the glass transition temperature (555°C), the surface quality decreased a lot. The laser damage test was performed, and the specimen heated at 450°C showed an improvement in LIDT.

Ureolytic/Non-Ureolytic Bacteria Co-Cultured Self-Healing Agent for Cementitious Materials Crack Repair

Directory of Open Access Journals (Sweden)

Hyeong Min Son

2018-05-01

Full Text Available The present study investigated the CaCO3 precipitation performance of ureolytic and non-ureolytic bacteria co-cultured as a self-healing agent for cementitious materials crack repair. Three different inoculum ratios of ureolytic Sporosarcina pasteurii and non-ureolytic Bacillus thuringiensis (10:0, 8:2, or 5:5 were used. The effect of coculturing ureolytic and non-ureolytic bacteria on microbial metabolism was investigated by measuring the rate of growth in urea-containing medium and the rate of NH4+ and CaCO3 production in urea–calcium lactate medium. The self-healing efficiency of co-cultured bacteria was examined by exposing cement mortar specimens with predefined cracks to media containing single urease-producing or co-cultured bacteria. The obtained results provide new findings, where CaCO3 precipitation is improved by co-culturing ureolytic and non-ureolytic bacteria, owing to the relatively faster growth rate of non-ureolytic bacteria. The crack filling rate correlated with the width of crack, in particular, specimens with a smaller crack width showed the faster filling effect, indicating that the crack width can be a dominant factor influencing the CaCO3 precipitation capacity of co-cultured bacteria.

Setup of Extruded Cementitious Hollow Tubes as Containing/Releasing Devices in Self-Healing Systems

Directory of Open Access Journals (Sweden)

Alessandra Formia

2015-04-01

Full Text Available The aim of this research is to produce self-healing cementitious composites based on the use of cylindrical capsules containing a repairing agent. Cementitious hollow tubes (CHT having two different internal diameters (of 2 mm and 7.5 mm were produced by extrusion and used as containers and releasing devices for cement paste/mortar healing agents. Based on the results of preliminary mechanical tests, sodium silicate was selected as the healing agent. The morphological features of several mix designs used to manufacture the extruded hollow tubes, as well as the coatings applied to increase the durability of both core and shell materials are discussed. Three-point bending tests were performed on samples produced with the addition of the above-mentioned cementitious hollow tubes to verify the self-healing effectiveness of the proposed solution. Promising results were achieved, in particular when tubes with a bigger diameter were used. In this case, a substantial strength and stiffness recovery was observed, even in specimens presenting large cracks (>1 mm. The method is inexpensive and simple to scale up; however, further research is needed in view of a final optimization.

Ultrasensitive Wearable Soft Strain Sensors of Conductive, Self-healing, and Elastic Hydrogels with Synergistic "Soft and Hard" Hybrid Networks.

Science.gov (United States)

Liu, Yan-Jun; Cao, Wen-Tao; Ma, Ming-Guo; Wan, Pengbo

2017-08-02

Robust, stretchable, and strain-sensitive hydrogels have recently attracted immense research interest because of their potential application in wearable strain sensors. The integration of the synergistic characteristics of decent mechanical properties, reliable self-healing capability, and high sensing sensitivity for fabricating conductive, elastic, self-healing, and strain-sensitive hydrogels is still a great challenge. Inspired by the mechanically excellent and self-healing biological soft tissues with hierarchical network structures, herein, functional network hydrogels are fabricated by the interconnection between a "soft" homogeneous polymer network and a "hard" dynamic ferric (Fe 3+ ) cross-linked cellulose nanocrystals (CNCs-Fe 3+ ) network. Under stress, the dynamic CNCs-Fe 3+ coordination bonds act as sacrificial bonds to efficiently dissipate energy, while the homogeneous polymer network leads to a smooth stress-transfer, which enables the hydrogels to achieve unusual mechanical properties, such as excellent mechanical strength, robust toughness, and stretchability, as well as good self-recovery property. The hydrogels demonstrate autonomously self-healing capability in only 5 min without the need of any stimuli or healing agents, ascribing to the reorganization of CNCs and Fe 3+ via ionic coordination. Furthermore, the resulted hydrogels display tunable electromechanical behavior with sensitive, stable, and repeatable variations in resistance upon mechanical deformations. Based on the tunable electromechanical behavior, the hydrogels can act as a wearable strain sensor to monitor finger joint motions, breathing, and even the slight blood pulse. This strategy of building synergistic "soft and hard" structures is successful to integrate the decent mechanical properties, reliable self-healing capability, and high sensing sensitivity together for assembling a high-performance, flexible, and wearable strain sensor.

An autonomic self-healing organogel with a photo-mediated modulus

KAUST Repository

Xiong, Yubing

2016-11-15

A new method is described for fabricating autonomic, self-healing, deformable organogels. We combined imidazolium-based poly(ionic liquid) (PIL) and azobenzene-grafted poly(carboxylic acid) (PAA-Azo) in N,N-dimethyl formamide. Further, complexing PIL with unirradiated (trans) or irradiated (cis) PAA-Azo tuned the elastic modulus of the organogel. © 2016 The Royal Society of Chemistry.

An autonomic self-healing organogel with a photo-mediated modulus

KAUST Repository

Xiong, Yubing; Chen, Zhijun; Wang, Hong; Ackermann, Lisa Maria; Klapper, Markus; Butt, Hans Jü rgen; Wu, Si

2016-01-01

A new method is described for fabricating autonomic, self-healing, deformable organogels. We combined imidazolium-based poly(ionic liquid) (PIL) and azobenzene-grafted poly(carboxylic acid) (PAA-Azo) in N,N-dimethyl formamide. Further, complexing PIL with unirradiated (trans) or irradiated (cis) PAA-Azo tuned the elastic modulus of the organogel. © 2016 The Royal Society of Chemistry.

Synthesis of alumina ceramic encapsulation for self-healing materials on thermal barrier coating

Science.gov (United States)

Golim, O. P.; Prastomo, N.; Izzudin, H.; Hastuty, S.; Sundawa, R.; Sugiarti, E.; Thosin, K. A. Z.

2018-03-01

Durability of Thermal Barrier Coating or TBC can be optimized by inducing Self-Healing capabilities with intermetallic materials MoSi2. Nevertheless, high temperature operation causes the self-healing materials to become oxidized and lose its healing capabilities. Therefore, a method to introduce ceramic encapsulation for MoSi2 is needed to protect it from early oxidation. The encapsulation process is synthesized through a simple precipitation method with colloidal aluminum hydroxide as precursor and variations on calcination process. Semi-quantitative analysis on the synthesized sample is done by using X-ray diffraction (XRD) method. Meanwhile, qualitative analysis on the morphology of the encapsulation was carried out by using Scanning Electron Microscope (SEM) and Field Emission Scanning Electron Microscope (FESEM) equipped with dual Focus Ion Beam (FIB). The result of the experiment shows that calcination process significantly affects the final characteristic of encapsulation. The optimum encapsulation process was synthesized by colloidal aluminum hydroxide as a precursor, with a double step calcination process in low pressure until 900 °C.

Autonomous Dynamically Self-Organizing and Self-Healing Distributed Hardware Architecture - the eDNA Concept

Science.gov (United States)

Boesen, Michael Reibel; Madsen, Jan; Keymeulen, Didier

2011-01-01

This paper presents the current state of the autonomous dynamically self-organizing and self-healing electronic DNA (eDNA) hardware architecture (patent pending). In its current prototype state, the eDNA architecture is capable of responding to multiple injected faults by autonomously reconfiguring itself to accommodate the fault and keep the application running. This paper will also disclose advanced features currently available in the simulation model only. These features are future work and will soon be implemented in hardware. Finally we will describe step-by-step how an application is implemented on the eDNA architecture.

Automated Manufacture of Damage Detecting, Self-Healing Composite Cryogenic Pressure Vessels, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — After successfully demonstrating the basic functionality of a damage-detecting, self-healing 'smart' material system in Phase I, Aurora and UMass Lowell aim to...

An in vitro comparison of the accuracy of implant impressions with coded healing abutments and different implant angulations.

Science.gov (United States)

Al-Abdullah, Khaled; Zandparsa, Roya; Finkelman, Matthew; Hirayama, Hiroshi

2013-08-01

Fabricating implant definitive casts with CAD/CAM technology (Robocasts) from coded healing abutment impressions represents a simpler and innovative alternative to conventional implant impression techniques. However, information about the accuracy of the impressions and the resultant definitive casts is limited. The purpose of the study was to evaluate the accuracy of the Robocasts and compare them to those definitive casts fabricated with conventional implant impression techniques (open tray with splinted impression copings technique). A reference epoxy resin cast was fabricated and shaped to simulate a dental arch. Two regular platform implant replicas (Biomet 3i Certain, 4.1 mm diameter and 15 mm length) with internal connections were placed 10 mm apart with a 10-degree convergence for one side of the reference resin cast and a 30-degree convergence for the other. Coded healing abutments (Encode) were placed at 3 different heights above the level of the soft tissue replication material (approximately 1, 2, and 4 mm) and served as test groups (E1, E2, and E4), and open trays with splinted impression copings (OTSC) served as a control group. The control group was compared to the impressions of the coded healing abutments by using a standardized measurement protocol. Impressions were made for each group (n=18) and poured with vacuum mixed (100 g powder/20 mL water) Type IV dental stone. The vertical discrepancy (Z axis) between 2 prefabricated passively fitting titanium reference frameworks and the platforms of the implant replicas was measured with an optical comparator applying the 1 screw test. Data were analyzed with Kruskal-Wallis and post-hoc Mann-Whitney U tests, as well as the Wilcoxon signed-rank tests. The Bonferroni correction was used to account for multiple comparisons. The significance level (α) used in a given set of tests was equal to .05 divided by the number of tests performed in that set. The median vertical discrepancy of each coded healing

Self-healing properties of recycled asphalt mixtures containing metal waste: An approach through microwave radiation heating.

Science.gov (United States)

González, A; Norambuena-Contreras, J; Storey, L; Schlangen, E

2018-05-15

The concept of self-healing asphalt mixtures by bitumen temperature increase has been used by researchers to create an asphalt mixture with crack-healing properties by microwave or induction heating. Metals, normally steel wool fibers (SWF), are added to asphalt mixtures prepared with virgin materials to absorb and conduct thermal energy. Metal shavings, a waste material from the metal industry, could be used to replace SWF. In addition, reclaimed asphalt pavement (RAP) could be added to these mixtures to make a more sustainable road material. This research aimed to evaluate the effect of adding metal shavings and RAP on the properties of asphalt mixtures with crack-healing capabilities by microwave heating. The research indicates that metal shavings have an irregular shape with widths larger than typical SWF used with asphalt self-healing purposes. The general effect of adding metal shavings was an improvement in the crack-healing of asphalt mixtures, while adding RAP to mixtures with metal shavings reduced the healing. The average surface temperature of the asphalt samples after microwave heating was higher than temperatures obtained by induction heating, indicating that shavings are more efficient when mixtures are heated by microwave radiation. CT scan analysis showed that shavings uniformly distribute in the mixture, and the addition of metal shavings increases the air voids. Overall, it is concluded that asphalt mixtures with RAP and waste metal shavings have the potential of being crack-healed by microwave heating. Copyright © 2018 Elsevier Ltd. All rights reserved.

Soft Asphalt and Double Otta Seal—Self-Healing Sustainable Techniques for Low-Volume Gravel Road Rehabilitation

Directory of Open Access Journals (Sweden)

Audrius Vaitkus

2018-01-01

Full Text Available Increased traffic flow on low-volume gravel roads and deficiencies of national road infrastructure, are increasingly apparent in Lithuania. Gravel roads do not comply with requirements, resulting in low driving comfort, longer travelling time, faster vehicle amortization, and dustiness. The control of dustiness is one of the most important road maintenance activities on gravel roads. Another important issue is the assurance of required driving comfort and safety. Soft asphalt and Otta Seal technologies were proposed as a sustainable solution for the improvement of low-volume roads in Lithuania. Five gravel roads were constructed with soft asphalt, and 13 gravel roads were sealed with double Otta Seal, in 2012. The main aim of this research was to check soft asphalt and double Otta Seal’s ability to self-heal, on the basis of the results of the qualitative visual assessment of pavement defects and distress. The qualitative visual assessment was carried out twice a year following the opening of the rehabilitated road sections. The results confirmed soft asphalt and double Otta Seal’s ability to self-heal. The healing effect was more than 13% and 19% on roads with soft asphalt and double Otta Seal, respectively. In addition, on some roads, all cracks observed in spring self-healed during summer.

Improvement of fatigue resistance of epoxy composite with microencapsulated epoxy-SbF5 self-healing system

Directory of Open Access Journals (Sweden)

X. J. Ye

2017-11-01

Full Text Available Rapid retardation and arresting of fatigue crack are successfully realized in the epoxy composite containing microencapsulated epoxy and ethanol solution of antimony pentafluoride-ethanol complex (SbF5·HOC2H5/HOC2H5. The effects of (i microcapsules induced-toughening, (ii hydrodynamic pressure crack tip shielding offered by the released healing agent, and (iii polymeric wedge and adhesive bonding of cured healing agent account for extension of fatigue life of the material. The two components of the healing agent can quickly react with each other soon after rupture of the microcapsules, and reconnect the crack only 20 seconds as of the test. The applied stress intensity range not only affects the healing efficiency, but also can be used to evaluate the healing speed. The present work offers a very fast healing system, and sets up a framework for characterizing speed of self-healing.

Clay club initiative: self-healing of fractures in clay-rich host rocks

International Nuclear Information System (INIS)

Horseman, S.T.; Cuss, R.J.; Reeves, H.J.

2004-01-01

The capacity of fractures in argillaceous rocks to self-heal (or become, with the passage of time, less conductive to groundwater) is often cited as a primary factor favouring the choice of such materials as host rocks for deep disposal. The underlying processes which contribute to self-healing can be broadly subdivided into: (a) mechanical and hydro-mechanical processes linked to the change in the stress field, movement of pore water, swelling, softening, plastic deformation and creep, and (b) geochemical processes linked to chemical alterations, transport in aqueous solution and the precipitation of minerals. Since chemical alteration can cause profound changes to the mechanical properties of argillaceous rocks, it is often difficult to draw a firm line between these two subdivisions. Based on the deliberations of the recent Cluster Conference in Luxembourg, there would appear to be some support for the use of the term 'self-sealing' for processes affecting fracture conductivity in argillaceous rock that are largely mechanical or hydro-mechanical in their origin. There are four main areas in which the self-healing capacity of the host rock becomes relevant to repository design and performance assessment: - potential for radionuclide transport within the excavation damage zone (EDZ); - design and performance of repository sealing systems; - potential impact of gas migration; - long-term performance considering erosional unloading, seismicity and fault reactivation. The presence of an EDZ is acknowledged to be a particularly important issue in performance assessment. Interconnection of fractures in the EDZ could lead to the development of a preferential flow path extending along the emplacement holes, access tunnels and shafts of a repository towards overlying aquifers and the biosphere. In the preliminary French Safety Analyses, for example, the treatment of scenarios relating to early seal failure have highlighted the hydraulic role of the damaged zone as a

Integration of the Reconfigurable Self-Healing eDNA Architecture in an Embedded System

Science.gov (United States)

Boesen, Michael Reibel; Keymeulen, Didier; Madsen, Jan; Lu, Thomas; Chao, Tien-Hsin

2011-01-01

In this work we describe the first real world case study for the self-healing eDNA (electronic DNA) architecture by implementing the control and data processing of a Fourier Transform Spectrometer (FTS) on an eDNA prototype. For this purpose the eDNA prototype has been ported from a Xilinx Virtex 5 FPGA to an embedded system consisting of a PowerPC and a Xilinx Virtex 5 FPGA. The FTS instrument features a novel liquid crystal waveguide, which consequently eliminates all moving parts from the instrument. The addition of the eDNA architecture to do the control and data processing has resulted in a highly fault-tolerant FTS instrument. The case study has shown that the early stage prototype of the autonomous self-healing eDNA architecture is expensive in terms of execution time.

Television and Children: five years after the Self-regulation Code

Directory of Open Access Journals (Sweden)

Mª Cruz López-de-Ayala-López, Ph.D.

2011-01-01

Full Text Available In the context of the technological transformations caused by the digital switchover in Television, the management and exploitation of DTT presents important challenges to service providers. One of the most outstanding challenges is the creation of contents that ensures minors’ correct education and protection against violence and harmful social behaviours. This article presents the results of a qualitative and quantitative study, conducted by the authors and other researchers from the Rey Juan Carlos University, aimed at verifying the effective application of the Self-regulation Code on TV Contents and Children that was signed by the main national and regional networks operating in Spain. The study examined all the programmes broadcast during the time of special protection for children introduced by the Self-regulation Code, by TVE 1, Antena 3, Cuatro, Tele5, La Sexta, and Telemadrid from September to December 2008 and from July to September 2009. Based on the results, the article offers a verdict on the degree of success with which the objectives of the Self-regulation Code have been met by the networks.

Construction of MDS self-dual codes from orthogonal matrices

OpenAIRE

Shi, Minjia; Sok, Lin; Solé, Patrick

2016-01-01

In this paper, we give algorithms and methods of construction of self-dual codes over finite fields using orthogonal matrices. Randomization in the orthogonal group, and code extension are the main tools. Some optimal, almost MDS, and MDS self-dual codes over both small and large prime fields are constructed.

Investigation of the Self-Healing Behavior of Sn-Bi Metal Matrix Composite Reinforced with NiTi Shape Memory Alloy Strips Under Flexural Loading

Science.gov (United States)

Poormir, Mohammad Amin; Khalili, Seyed Mohammad Reza; Eslami-Farsani, Reza

2018-06-01

Utilizing intelligent materials such as shape memory alloys as reinforcement in metal matrix composites is a novel method to mimic self-healing behavior. In this study, the bending behavior of a self-healing metal matrix composite made from Sn-13 wt.% Bi alloy as matrix and NiTi shape memory alloy (SMA) strips as reinforcement is investigated. Specimens were fabricated in different reinforcement vol.% (0.78, 1.55, 2.33) and in various pre-strains (0, 2, 6%) and were healed at three healing temperatures (170°C, 180°C, 190°C). Results showed that shape recovery was accomplished in all the specimens, but not all of them were able to withstand second loading after healing. Only specimens with 2.33 vol.% of SMA strips, 1.55 vol.% of SMA, and 6% pre-strain could endure bending force after healing, and they gained 35.31-51.83% of bending force self-healing efficiency.

An Innovative Approach to Control Steel Reinforcement Corrosion by Self-Healing

Directory of Open Access Journals (Sweden)

Dessi A. Koleva

2018-02-01

Full Text Available The corrosion of reinforced steel, and subsequent reinforced concrete degradation, is a major concern for infrastructure durability. New materials with specific, tailor-made properties or the establishment of optimum construction regimes are among the many approaches to improving civil structure performance. Ideally, novel materials would carry self-repairing or self-healing capacities, triggered in the event of detrimental influence and/or damage. Controlling or altering a material’s behavior at the nano-level would result in traditional materials with radically enhanced properties. Nevertheless, nanotechnology applications are still rare in construction, and would break new ground in engineering practice. An approach to controlling the corrosion-related degradation of reinforced concrete was designed as a synergetic action of electrochemistry, cement chemistry and nanotechnology. This contribution presents the concept of the approach, namely to simultaneously achieve steel corrosion resistance and improved bulk matrix properties. The technical background and challenges for the application of polymeric nanomaterials in the field are briefly outlined in view of this concept, which has the added value of self-healing. The credibility of the approach is discussed with reference to previously reported outcomes, and is illustrated via the results of the steel electrochemical responses and microscopic evaluations of the discussed materials.

An Innovative Approach to Control Steel Reinforcement Corrosion by Self-Healing

Science.gov (United States)

2018-01-01

The corrosion of reinforced steel, and subsequent reinforced concrete degradation, is a major concern for infrastructure durability. New materials with specific, tailor-made properties or the establishment of optimum construction regimes are among the many approaches to improving civil structure performance. Ideally, novel materials would carry self-repairing or self-healing capacities, triggered in the event of detrimental influence and/or damage. Controlling or altering a material’s behavior at the nano-level would result in traditional materials with radically enhanced properties. Nevertheless, nanotechnology applications are still rare in construction, and would break new ground in engineering practice. An approach to controlling the corrosion-related degradation of reinforced concrete was designed as a synergetic action of electrochemistry, cement chemistry and nanotechnology. This contribution presents the concept of the approach, namely to simultaneously achieve steel corrosion resistance and improved bulk matrix properties. The technical background and challenges for the application of polymeric nanomaterials in the field are briefly outlined in view of this concept, which has the added value of self-healing. The credibility of the approach is discussed with reference to previously reported outcomes, and is illustrated via the results of the steel electrochemical responses and microscopic evaluations of the discussed materials. PMID:29461495

Inkjet Assisted Creation of Self-Healing Layers Between Composite Plies

Science.gov (United States)

2013-07-29

technology into a prepreg manufacturing process. The approach consisted of depositing novel thermoplastic low-viscosity microdroplets with chemically and...mechanically comparable properties to epoxy matrix in aerospace grade composites onto fiber-reinforced epoxy prepregs before curing using an ink-jet... prepreg Cycom977-2. Double cantilever beam (DCB) and short beam shear (SBS) tests were used to evaluate the self-healing efficiency. It was shown

Thermally Self-Healing Polymeric Materials : The Next Step to Recycling Thermoset Polymers?

NARCIS (Netherlands)

Zhang, Youchun; Broekhuis, Antonius A.; Picchioni, Francesco

2009-01-01

We developed thermally self-healing polymeric materials on the basis of furan-functionalized, alternating thermosetting polyketones (PK-furan) and bis-maleimide by using the Diels-Alder (DA) and Retro-Diels-Alder (RDA) reaction sequence. PK-furan can be easily obtained under mild conditions by the

Evaluation of self-healing ability in protective coatings modified with combinations of layered double hydroxides and cerium molibdate nanocontainers filled with corrosion inhibitors

International Nuclear Information System (INIS)

Montemor, M.F.; Snihirova, D.V.; Taryba, M.G.; Lamaka, S.V.; Kartsonakis, I.A.; Balaskas, A.C.; Kordas, G.C.; Tedim, J.; Kuznetsova, A.; Zheludkevich, M.L.; Ferreira, M.G.S.

2012-01-01

Nowadays, there is a strong demand on the search of thinner, but more effective organic coatings for corrosion protection of metallic substrates, like galvanised steel, used in the automotive industry. In order to guarantee effective corrosion protection of these coatings, and because chromate-based pigments cannot be used, one of the most attractive strategies consists on the modification of the organic matrix with nano-additives filled with corrosion inhibitors, which can be released to the active sites. In this work, two different nano-additives are explored as potential self-healing materials for the development of active protective coatings. These additives are layered double hydroxides and cerium molybdate hollow nanospheres loaded with mercaptobenzothiazole, as a corrosion inhibitor. These additives were added to epoxy primers, individually, or combining the two nanoadditives in the same layer. The electrochemical behaviour and the potential of self-healing ability were studied by electrochemical impedance spectroscopy, scanning vibrating electrode technique and scanning ion-selective electrode technique. The results reveal that both types of nanocontainers can provide effective corrosion inhibition on artificial induced defects, at different stages of the degradation process. Moreover, the results also show that there is a synergistic effect concerning corrosion inhibition and self-healing potential when a mixture of the two nanocontainers is used. The mechanism of self healing is presented and discussed in terms of effect of organic inhibitor and role of the nanocontainers, including effect of cerium ions released from cerium molibdate nanoparticles.

Construction of self-dual codes in the Rosenbloom-Tsfasman metric

Science.gov (United States)

Krisnawati, Vira Hari; Nisa, Anzi Lina Ukhtin

2017-12-01

Linear code is a very basic code and very useful in coding theory. Generally, linear code is a code over finite field in Hamming metric. Among the most interesting families of codes, the family of self-dual code is a very important one, because it is the best known error-correcting code. The concept of Hamming metric is develop into Rosenbloom-Tsfasman metric (RT-metric). The inner product in RT-metric is different from Euclid inner product that is used to define duality in Hamming metric. Most of the codes which are self-dual in Hamming metric are not so in RT-metric. And, generator matrix is very important to construct a code because it contains basis of the code. Therefore in this paper, we give some theorems and methods to construct self-dual codes in RT-metric by considering properties of the inner product and generator matrix. Also, we illustrate some examples for every kind of the construction.

Biochemical process of ureolysis-based microbial CaCO3 precipitation and its application in self-healing concrete.

Science.gov (United States)

Xu, Jing; Wang, Xianzhi; Wang, Binbin

2018-04-01

Urea hydrolysis has already been considered as the most effective pathway for microbially induced CaCO 3 precipitation (MICP). The present work first studied the combination of several key factors including initial pH, temperature, and dosage of urea, which contribute to the biochemical process of MICP. Under an amiable condition of pH and temperature, the dosage of urea has a significant impact on the rate of urea degradation and CaCO 3 precipitation. A bacteria-based self-healing system was developed by loading healing agents on ceramsite carriers. The self-healing efficiency was evaluated by visual inspection on crack closure, compressive strength regain, and capillary water absorption. A preferable healing effectiveness was obtained when the bacteria and organic nutrients were co-immobilized in carriers. Image analysis showed that cracks up to 273 μm could be healed with a crack closure ratio of 86% in 28 days. The compressive strength regain increased 24% and the water absorption coefficient decreased 27% compared to the reference. The findings indicated a promising application of ureolysis-based MICP in restoring the mechanical properties and enhancing the durability of concrete.

Optimization of process factors for self-healing vanadium-based conversion coating on AZ31 magnesium alloy

Science.gov (United States)

Li, Kun; Liu, Junyao; Lei, Ting; Xiao, Tao

2015-10-01

A self-healing vanadium-based conversion coating was prepared on AZ31 magnesium alloy. The optimum operating conditions including vanadia solution concentration, pH and treating temperature for obtaining the best corrosion protective vanadia coatings and improved localized corrosion resistance to the magnesium substrate were determined by an orthogonal experiment design. Surface morphology and composition of the resultant conversion coatings were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The self-healing behavior of the coating was investigated by cross-cut immersion test and electrochemical impedance spectroscopy (EIS) measurements in 3.5% NaCl solution.

Self-healing Anticorrosion Coatings for Gas Pipelines and Storage Tanks

Energy Technology Data Exchange (ETDEWEB)

Luckachan, G. E.; Mittal, V. [The Petroleum Institute, Abudhabi (United Arab Emirates)

2016-10-15

In the present study, chitosan based self-healing anticorrosion coatings were prepared by layer by layer (lbl) addition of chitosan (Ch) and polyvinyl butyral (PVB) on mild carbon steel substrate. Chitosan coatings exhibited enhanced coating stability and corrosion resistance in aggressive environments by the application of a PVB top layer. Chitosan layer in the lbl coatings have been modified by using glutaraldehyde (Glu) and silica (SiO{sub 2}). Performance of different coatings was tested using electrochemical impedance spectroscopy and immersion test. The best anticorrosion performance was observed in case of 10 % Ch{sub S}iO{sub 2P}VB coatings, which withstand immersion test over 25 days in 0.5 M salt solution without visible corrosion. 10 % Ch{sub S}iO{sub 2} coatings without the PVB top layer didn't last more than 3days. Application of PVB top layer sealed the defects in the chitosan pre-layer and improved its hydrophobic nature as well. Raman spectra and SEM of steel surfaces after corrosion study and removal of PVB{sub C}h/Glu{sub P}VB coatings showed a passive layer of iron oxide, attributing to the self-healing nature of these coatings. Conducting particle like graphene reinforcement of chitosan in the lbl coatings enhanced corrosion resistance of chitosan coatings.

Self-healing anticorrosive organic coating based on an encapsulated water reactive silyl ester: synthesis and proof of concept

NARCIS (Netherlands)

García, S.J.; Fischer, H.R.; White, P.A.; Mardel, J.; González-García, Y.; Mol, J.M.C.; Hughes, A.E.

2011-01-01

In this paper a self-healing anticorrosive organic coating based on an encapsulated water reactive organic agent is presented. A reactive silyl ester is proposed as a new organic reactive healing agent and its synthesis, performance, incorporation into an organic coating and evaluation of

Designing Networks that are Capable of Self-Healing and Adapting

Science.gov (United States)

2017-04-01

from statistical mechanics, combinatorics, boolean networks, and numerical simulations, and inspired by design principles from biological networks, we... principles for self-healing networks, and applications, and construct an all-possible-paths model for network adaptation. 2015-11-16 UNIT CONVERSION...kg m –3 ) pound-force (lbf avoirdupois) 4.448 222 newton (N) Energy/Work/Power electron volt (eV) 1.602 177 × 10 –19 joule (J) erg 1 × 10 –7

Healing Magazine, Volume 8, 2003.

Science.gov (United States)

2003

This volume of "Healing Magazine" features practical, clinical information aimed at sharing current work in children's mental health. The first issue contains articles on intervention for self-injurious behavior, providing school-based grief groups, effectively using time-out as a parenting tool, and KidsPeace's suicide prevention…

Thermosetting epoxy resin/thermoplastic system with combined shape memory and self-healing properties

International Nuclear Information System (INIS)

Yao, Yongtao; Wang, Jingjie; Lu, Haibao; Liu, Yanju; Leng, Jinsong; Xu, Ben; Fu, Yongqing

2016-01-01

A novel and facile strategy was proposed to construct a thermosetting/thermoplastic system with both shape memory and self-healing properties based on commercial epoxy resin and poly(ϵ-caprolactone)-PCL. Thermoplastic material is capable of re-structuring and changing the stiffness/modulus when the temperature is above melting temperature. PCL microfiber was used as a plasticizer in epoxy resin–based blends, and served as a ‘hard segment’ to fix a temporary shape of the composites during shape memory cycles. In this study, the electrospun PCL membrane with a porous network structure enabled a homogenous PCL fibrous distribution and optimized interaction between fiber and epoxy resin. The self-healing capability is achieved by phase transition during curing of the composites. The mechanism of the shape memory effect of the thermosetting (rubber)/thermoplastic composite is attributed to the structural design of the thermoplastic network inside the thermosetting resin/rubber matrix. (paper)

Bacillus sphaericus LMG 22257 is physiologically suitable for self-healing concrete.

Science.gov (United States)

Wang, Jianyun; Jonkers, Henk M; Boon, Nico; De Belie, Nele

2017-06-01

The suitability of using a spore-forming ureolytic strain, Bacillus sphaericus, was evaluated for self-healing of concrete cracks. The main focus was on alkaline tolerance, calcium tolerance, oxygen dependence, and low-temperature adaptability. Experimental results show that B. sphaericus had a good tolerance. It can grow and germinate in a broad range of alkaline pH. The optimal pH range is 7 ∼ 9. High alkaline conditions (pH 10 ∼ 11) slow down but not stop the growth and germination. Oxygen was strictly needed during bacterial growth and germination, but not an essential factor during bacterial urea decomposition. B. sphaericus also had a good Ca tolerance, especially at a high bacterial concentration of 10 8  cells/mL; no significant influence was observed on bacterial ureolytic activity of the presence of 0.9M Ca 2+ . Furthermore, at a low temperature (10 °C), bacterial spores germinated and revived ureolytic activity with some retardation. However, this retardation can be counteracted by using a higher bacterial concentration and by supplementing yeast extract. It can be concluded that B. sphaericus is a suitable bacterium for application in bacteria-based self-healing concrete.

A Study on the Manufacturing Properties of Crack Self-Healing Capsules Using Cement Powder for Addition to Cement Composites

OpenAIRE

Choi, Yun-Wang; Oh, Sung-Rok; Choi, Byung-Keol

2017-01-01

We fabricated crack self-healing capsules using cement powder for mixing into cement composites and evaluated the properties of the capsule manufacturing process in this study. The manufacture of the self-healing capsules is divided into core production processing of granulating cement in powder form and a coating process for creating a wall on the surfaces of the granulated cement particles. The produced capsules contain unhardened cement and can be mixed directly with the cement composite m...

Induction healing of asphalt mixes with steel slag

NARCIS (Netherlands)

Apostolidis, P.; Liu, X.; Wang, H.; van de Ven, M.F.C.; Scarpas, Athanasios

2018-01-01

Asphaltic mixes are self-healing materials since they have the capacity to close internal microcracks at higher temperatures or under external force. To trigger their self-healing, asphalt mixes modified with inductive agents can be heated and in that way healed through applying alternating magnetic

Temperature Scanning Stress Relaxation of an Autonomous Self-Healing Elastomer Containing Non-Covalent Reversible Network Junctions

Directory of Open Access Journals (Sweden)

Amit Das

2018-01-01

Full Text Available In this work, we report about the mechanical relaxation characteristics of an intrinsically self-healable imidazole modified commercial rubber. This kind of self-healing rubber was prepared by melt mixing of 1-butyl imidazole with bromo-butyl rubber (bromine modified isoprene-isobutylene copolymer, BIIR. By this melt mixing process, the reactive allylic bromine of bromo-butyl rubber was converted into imidazole bromide salt. The resulting development of an ionic character to the polymer backbone leads to an ionic association of the groups which ultimately results to the formation of a network structure of the rubber chains. The modified BIIR thus behaves like a robust crosslinked rubber and shows unusual self-healing properties. The non-covalent reversible network has been studied in detail with respect to stress relaxation experiments, scanning electron microscopic and X-ray scattering.

Low Complexity Tail-Biting Trellises for Some Extremal Self-Dual Codes

OpenAIRE

Olocco , Grégory; Otmani , Ayoub

2002-01-01

International audience; We obtain low complexity tail-biting trellises for some extremal self-dual codes for various lengths and fields such as the [12,6,6] ternary Golay code and a [24,12,8] Hermitian self-dual code over GF(4). These codes are obtained from a particular family of cyclic Tanner graphs called necklace factor graphs.

Static and fatigue tensile properties of cross-ply laminates containing vascules for self-healing applications

International Nuclear Information System (INIS)

Luterbacher, R; Trask, R S; Bond, I P

2016-01-01

The effect of including hollow channels (vascules) within cross-ply laminates on static tensile properties and fatigue performance is investigated. No change in mechanical properties or damage formation is observed when a single vascule is included in the 0/90 interface, representing 0.5% of the cross sectional area within the specimen. During tensile loading, matrix cracks develop in the 90° layers leading to a reduction of stiffness and strength (defined as the loss of linearity) and a healing agent is injected through the vascules in order to heal them and mitigate the caused degradation. Two different healing agents, a commercial low viscosity epoxy resin (RT151, Resintech) and a toughened epoxy blend (bespoke, in-house formulation) have been used to successfully recover stiffness under static loading conditions. The RT151 system recovered 75% of the initial failure strength, whereas the toughened epoxy blend achieved a recovery of 67%. Under fatigue conditions, post healing, a rapid decay of stiffness was observed as the healed damage re-opened within the first 2500 cycles. This was caused by the high fatigue loading intensity, which was near the static failure strength of the healing resin. However, the potential for ameliorating (via self-healing or autonomous repair) more diffuse transverse matrix damage via a vascular network has been shown. (paper)

Self-healing polymeric composite material design, failure analysis and future outlook: A review

CSIR Research Space (South Africa)

Mphahlele, Keletso

2017-10-01

Full Text Available , as well as the intrinsic organization of polymer chains [84,93–96]. Polymers 2017, 9, 535 10 of 22 Perhaps the two most studied interactions so far are those found in ionomers for ballistic [82,97] and coating applications and hydrogen bonding represented... by the well-defined ureidopyrimidinone constituent and the use of randomly branched oligomers equipped with self-complementary and complementary hydrogen bonding groups [82]. The self-healing method of ionomers originates from the intrinsic chemical structure...

Self-healing guar gum and guar gum-multiwalled carbon nanotubes nanocomposite gels prepared in an ionic liquid.

Science.gov (United States)

Sharma, Mukesh; Mondal, Dibyendu; Mukesh, Chandrakant; Prasad, Kamalesh

2013-10-15

Guar gum is a galactomannan extracted from the seed of the leguminous shrub Cyamopsis tetragonoloba. It was found to form a soft viscoelastic gel in 1-butyl-3-methylimidazolium chloride, an ionic liquid at an optimized concentration of 10%w/v. A nanocomposite gel of the gum with enhanced strength could be prepared with 0.2%w/v of multiwalled carbon nanotubes (MWCNTs) in the ionic liquid. When the gels thus prepared were subjected to surface fractures or bisected completely, they found to self-heal at room temperature without any external interventions. The self-healing process could be repeated several times. These viscoelastic gel systems showed thixotropic nature and recovery of the storage modulus with time for several cycles was observed upon rheological investigations. The interaction took place between ionic liquid, guar gum and MWCNT was studied by SEM, TEM, FT-IR, powder XRD and rheometry. The results suggested that, upon standing at room temperature development of electrostatic interactions and the van der Waals interactions among the ionic liquid molecules facilitated the formation of reversible noncovalent bonds and eventually activated the self-healing in the gel systems through appropriate chain entanglements. Copyright © 2013 Elsevier Ltd. All rights reserved.

Micromechanical characterization of single-walled carbon nanotube reinforced ethylidene norbornene nanocomposites for self-healing applications

International Nuclear Information System (INIS)

Aïssa, B; Haddad, E; Jamroz, W; Hassani, S; Farahani, R D; Therriault, D; Merle, P G

2012-01-01

We report on the fabrication of self-healing nanocomposite materials, consisting of single-walled carbon nanotube (SWCNT) reinforced 5-ethylidene-2-norbornene (5E2N) healing agent—reacted with ruthenium Grubbs catalyst—by means of ultrasonication, followed by a three-roll mixing mill process. The kinetics of the 5E2N ring opening metathesis polymerization (ROMP) was studied as a function of the reaction temperature and the SWCNT loads. Our results demonstrated that the ROMP reaction was still effective in a large temperature domain ( − 15–45 °C), occurring at very short time scales (less than 1 min at 40 °C). On the other hand, the micro-indentation analysis performed on the SWCNT/5E2N nanocomposite material after its ROMP polymerization showed a clear increase in both the hardness and the Young modulus—up to nine times higher than that of the virgin polymer—when SWCNT loads range only from 0.1 to 2 wt%. The approach demonstrated here opens new prospects for using carbon nanotube and healing agent nanocomposite materials for self-repair functionality, especially in a space environment. (paper)

Self-healing woven glass fabric/epoxy composites with the healant consisting of micro-encapsulated epoxy and latent curing agent

International Nuclear Information System (INIS)

Yin Tao; Zhou Lin; Rong Minzhi; Zhang Mingqiu

2008-01-01

This paper reports a study of self-healing woven glass fabric reinforced epoxy composites. The healing agent was a two-component one synthesized in the authors' laboratory, which consisted of epoxy-loaded urea-formaldehyde microcapsules as the polymerizable binder and CuBr 2 (2-methylimidazole) 4 (CuBr 2 (2-MeIm) 4 ) as the latent hardener. Both the microcapsules and the matching catalyst were pre-embedded and pre-dissolved in the composites' matrix, respectively. When the microcapsules are split by propagating cracks, the uncured epoxy can be released into the damaged areas and then consolidated under the catalysis of CuBr 2 (2-MeIm) 4 that was homogeneously distributed in the composites' matrix on a molecular scale. As a result, the cracked faces can be bonded together. The influence of the content of the self-healing agent on the composites' tensile properties, interlaminar fracture toughness and healing efficiency was evaluated. It was found that a healing efficiency over 70% relative to the fracture toughness of virgin composites was obtained in the case of 30 wt% epoxy-loaded microcapsules and 2 wt% latent hardener

Integration of the Reconfigurable Self-Healing eDNA Architecture in an Embedded System

DEFF Research Database (Denmark)

Boesen, Michael Reibel; Keymeulen, Didier; Madsen, Jan

2011-01-01

In this work we describe the first real world case study for the self-healing eDNA (electronic DNA) architecture by implementing the control and data processing of a Fourier Transform Spectrometer (FTS) on an eDNA prototype. For this purpose the eDNA prototype has been ported from a Xilinx Virtex 5...

Mechanically Robust 3D Nanostructure Chitosan-Based Hydrogels with Autonomic Self-Healing Properties.

Science.gov (United States)

Karimi, Ali Reza; Khodadadi, Azam

2016-10-12

Fabrication of hydrogels based on chitosan (CS) with superb self-healing behavior and high mechanical and electrical properties has become a challenging and fascinating topic. Most of the conventional hydrogels lack these properties at the same time. Our objectives in this research were to synthesize, characterize, and evaluate the general properties of chitosan covalently cross-linked with zinc phthalocyanine tetra-aldehyde (ZnPcTa) framework. Our hope was to access an unprecedented self-healable three-dimensional (3D) nanostructure that would harvest the superior mechanical and electrical properties associated with chitosan. The properties of cross-linker such as the structure, steric effect, and rigidity of the molecule played important roles in determining the microstructure and properties of the resulting hydrogels. The tetra-functionalized phthalocyanines favor a dynamic Schiff-base linkage with chitosan to form a 3D porous nanostructure. Based on this strategy, the self-healing ability, as demonstrated by rheological recovery and macroscopic and microscopic observations, is introduced through dynamic covalent Schiff-base linkage between NH 2 groups in CS and benzaldehyde groups at cross-linker ends. The hydrogel was characterized using FT-IR, NMR, UV/vis, and rheological measurements. In addition, cryogenic scanning electron microscopy (cryo-SEM) was employed as a technique to visualize the internal morphology of the hydrogels. Study of the surface morphology of the hydrogel showed a 3D porous nanostructure with uniform morphology. Furthermore, incorporating the conductive nanofillers, such as carbon nanotubes (CNTs), into the structure can modulate the mechanical and electrical properties of the obtained hydrogels. Interestingly, these hydrogel nanocomposites proved to have very good film-forming properties, high modulus and strength, acceptable electrical conductivity, and excellent self-healing properties at neutral pH. Such properties can be finely tuned

Wear-triggered self-healing behavior on the surface of nanocrystalline nickel aluminum bronze/Ti3SiC2 composites

Science.gov (United States)

Zhai, Wenzheng; Lu, Wenlong; Zhang, Po; Wang, Jian; Liu, Xiaojun; Zhou, Liping

2018-04-01

Self-healing can protect materials from diverse damages, but is intrinsically difficult in metals. This paper demonstrates a potential method through a simultaneous decomposition and oxidation of Ti3SiC2 to achieve healing of stress cracking on the surface of nickel aluminum bronze (NAB)/Ti3SiC2 nanocrystalline composites during fretting wear. At the finest nanocrystalline materials, a crack recovery would be attained at 76.5%. The repetitive fretting wear leads to a modest amount of 'flowability' of Ti3SiC2 toward the crack, facilitating crack recovery. Along with the wear-triggered self-healing, the NAB/Ti3SiC2 shows an improved tribological performance with the stable decreased friction torque due to the formation of lubrication TiO2 oxide.

Novel antifouling self-healing poly(carboxybetaine methacrylamide-co-HEMA) nanocomposite hydrogels with superior mechanical properties

NARCIS (Netherlands)

Kostina, Nina Yu.; Sharifi, Shahriar; Pereira, Andres de los Santos; Michalek, Jiri; Grijpma, Dirk W.; Rodriguez-Emmenegger, Cesar

2013-01-01

Novel antifouling highly wettable hydrogels with superior mechanical and self-healing properties are presented. Hydrogels were prepared by UV-initiated copolymerisation of non-fouling zwitterionic carboxybetaine methacrylamide (CBMAA-3) and 2-hydroxyethyl methacrylate (HEMA) in the presence of

A parametric study on hydraulic conductivity and self-healing properties of geotextile clay liners used in landfills.

Science.gov (United States)

Parastar, Fatemeh; Hejazi, Sayyed Mahdi; Sheikhzadeh, Mohammad; Alirezazadeh, Azam

2017-11-01

Nowadays, the raise of excessive generation of solid wastes is considered as a major environmental concern due to the fast global population growth. The contamination of groundwater from landfill leachate compromises every living creature. Geotextile clay liner (GCL) that has a sandwich structure with two fibrous sheets and a clay core can be considered as an engineered solution to prevent hazardous pollutants from entering into groundwater. The main objective of the present study is therefore to enhance the performance of GCL structures. By changing some structural factors such as clay type (sodium vs. calcium bentonite), areal density of clay, density of geotextile, geotextile thickness, texture type (woven vs. nonwoven), and needle punching density a series of GCL samples were fabricated. Water pressure, type of cover soil and overburden pressure were the environmental variables, while the response variables were hydraulic conductivity and self-healing rate of GCL. Rigid wall constant head permeability test was conducted on all the samples. The outlet water flow was measured and evaluated at a defined time period and the hydraulic conductivity was determined for each sample. In the final stage, self-healing properties of samples were investigated and an analytical model was used to explain the results. It was found that higher Montmorillonite content of clay, overburden pressure, needle punching density and areal density of clay poses better self-healing properties and less hydraulic conductivity, meanwhile, an increase in water pressure increases the hydraulic conductivity. Moreover, the observations were aligned with the analytical model and indicated that higher fiber inclusion as a result of higher needle-punching density produces closer contact between bentonite and fibers, reduces hydraulic conductivity and increases self-healing properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

On the development of polypyrrole coatings with self-healing properties for iron corrosion protection

International Nuclear Information System (INIS)

Paliwoda-Porebska, G.; Stratmann, M.; Rohwerder, M.; Potje-Kamloth, K.; Lu, Y.; Pich, A.Z.; Adler, H.-J.

2005-01-01

This paper presents studies on the efficacy and on the limits of polypyrrole (Ppy) doped with either MoO 4 2- or [PMo 12 O 40 ] 3- as self-healing corrosion protecting coatings. The kinetics of the cathodic delamination were studied by means of the Scanning Kelvin Probe (SKP). This method, in combination with cyclic voltammetry, UV-visible spectroscopy (UV-vis) and X-ray photoelectron spectroscopy (XPS), shows a potential driven anion release from the Ppy coating that results in an inhibition of the corrosion process taking place in the defect. Thus, an intelligent release of inhibitor occurs only when the potential at the interface decreases. Inhibitor anions are released only due to an active defect. However, the release mechanism can be easily negatively affected by the presence of small cations and/or by too high pH values at the buried interface. Hence, such a self-healing coating has to be carefully designed in order to ensure an effective performance

An autonomously electrically self-healing liquid metal-elastomer composite for robust soft-matter robotics and electronics.

Science.gov (United States)

Markvicka, Eric J; Bartlett, Michael D; Huang, Xiaonan; Majidi, Carmel

2018-07-01

Large-area stretchable electronics are critical for progress in wearable computing, soft robotics and inflatable structures. Recent efforts have focused on engineering electronics from soft materials-elastomers, polyelectrolyte gels and liquid metal. While these materials enable elastic compliance and deformability, they are vulnerable to tearing, puncture and other mechanical damage modes that cause electrical failure. Here, we introduce a material architecture for soft and highly deformable circuit interconnects that are electromechanically stable under typical loading conditions, while exhibiting uncompromising resilience to mechanical damage. The material is composed of liquid metal droplets suspended in a soft elastomer; when damaged, the droplets rupture to form new connections with neighbours and re-route electrical signals without interruption. Since self-healing occurs spontaneously, these materials do not require manual repair or external heat. We demonstrate this unprecedented electronic robustness in a self-repairing digital counter and self-healing soft robotic quadruped that continue to function after significant damage.

Rheo-mechanical model for self-healing asphalt pavement

International Nuclear Information System (INIS)

Gömze, A L; Gömze, L N

2017-01-01

Examining the rheological properties of different asphalt mixtures at different temperatures, pressures and deformation conditions on the combined rheo-tribometers the authors have found that the generally used Burgers-model doesn’t explain the deformation properties of asphalt mixtures and pavements under loading forces and loading pressures. To understand better the rheological and deformation properties of such complex materials like asphalt mixtures and pavements the authors used Malvern Mastersizer X laser granulometer, Bruker D8 Advance X-ray diffractometer, Hitachi TM 1000 Scanning Elektronmicroscope, Tristar 3000 specific surface tester and the combined rheo-tribometer developed and patented by the authors. After the complex investigation of different asphalt mixtures the authors have found a new, more complex rheological model for the asphalts including self-healing asphalt pavements. (paper)

Dual Cross-Linked Biofunctional and Self-Healing Networks to Generate User-Defined Modular Gradient Hydrogel Constructs.

Science.gov (United States)

Wei, Zhao; Lewis, Daniel M; Xu, Yu; Gerecht, Sharon

2017-08-01

Gradient hydrogels have been developed to mimic the spatiotemporal differences of multiple gradient cues in tissues. Current approaches used to generate such hydrogels are restricted to a single gradient shape and distribution. Here, a hydrogel is designed that includes two chemical cross-linking networks, biofunctional, and self-healing networks, enabling the customizable formation of modular gradient hydrogel construct with various gradient distributions and flexible shapes. The biofunctional networks are formed via Michael addition between the acrylates of oxidized acrylated hyaluronic acid (OAHA) and the dithiol of matrix metalloproteinase (MMP)-sensitive cross-linker and RGD peptides. The self-healing networks are formed via dynamic Schiff base reaction between N-carboxyethyl chitosan (CEC) and OAHA, which drives the modular gradient units to self-heal into an integral modular gradient hydrogel. The CEC-OAHA-MMP hydrogel exhibits excellent flowability at 37 °C under shear stress, enabling its injection to generate gradient distributions and shapes. Furthermore, encapsulated sarcoma cells respond to the gradient cues of RGD peptides and MMP-sensitive cross-linkers in the hydrogel. With these superior properties, the dual cross-linked CEC-OAHA-MMP hydrogel holds significant potential for generating customizable gradient hydrogel constructs, to study and guide cellular responses to their microenvironment such as in tumor mimicking, tissue engineering, and stem cell differentiation and morphogenesis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dilute self-healing hydrogels of silk-collagen-like block copolypeptides at neutral pH

NARCIS (Netherlands)

Golinska, M.D.; Wlodarczyk-Biegun, M.K.; Werten, M.W.T.; Cohen Stuart, M.A.; Wolf, de F.A.; Vries, de R.J.

2014-01-01

We report on self-healing, pH-responsive hydrogels that are entirely protein-based. The protein is a denovo designed recombinant triblock polypeptide of 66 kg/mol consisting of a silk-like middle block (GAGAGAGH)48, flanked by two long collagen-inspired hydrophilic random coil side blocks. The

A Study on the Manufacturing Properties of Crack Self-Healing Capsules Using Cement Powder for Addition to Cement Composites

Directory of Open Access Journals (Sweden)

Yun-Wang Choi

2017-01-01

Full Text Available We fabricated crack self-healing capsules using cement powder for mixing into cement composites and evaluated the properties of the capsule manufacturing process in this study. The manufacture of the self-healing capsules is divided into core production processing of granulating cement in powder form and a coating process for creating a wall on the surfaces of the granulated cement particles. The produced capsules contain unhardened cement and can be mixed directly with the cement composite materials because they are protected from moisture by the wall material. Therefore, the untreated cement is present in the form of a capsule within the cement composite, and hydration can be induced by moisture penetrating the crack surface in the event of cracking. In the process of granulating the cement, it is important to obtain a suitable consistency through the kneading agent and to maintain the moisture barrier performance of the wall material. We can utilize the results of this study as a basis for advanced self-healing capsule technology for cement composites.

The Essence of Healing from Sexual Violence: A Qualitative Metasynthesis

Science.gov (United States)

Draucker, Claire Burke; Martsolf, Donna S; Ross, Ratchneewan; Cook, Christina Benson; Stidham, Andrea Warner; Mweemba, Prudencia

2011-01-01

A qualitative metasynthesis was conducted to identify the essence of healing from sexual violence, as described by adults who experienced it as children or as adults. Based on the findings of 51 reports, four domains of healing were identified: (a) managing memories, (b) relating to important others, (c) seeking safety, and (c) reevaluating self. The ways of healing within each domain reflected opposing responses. The dialectical process identified for each of the four domains include, respectively: (a) calling forth memories, (b) regulating relationships with others, (c) constructing an “as-safe-as-possible” lifeworld, and (d) restoring a sense of self. These complex processes resulted in a new reality for the participants that was based on a greater sense of agency and provided a more satisfying life course. PMID:19415681

Microbial healing of cracks in concrete: a review.

Science.gov (United States)

Joshi, Sumit; Goyal, Shweta; Mukherjee, Abhijit; Reddy, M Sudhakara

2017-11-01

Concrete is the most widely used construction material of the world and maintaining concrete structures from premature deterioration is proving to be a great challenge. Early age formation of micro-cracking in concrete structure severely affects the serviceability leading to high cost of maintenance. Apart from conventional methods of repairing cracks with sealants or treating the concrete with adhesive chemicals to prevent the cracks from widening, a microbial crack-healing approach has shown promising results. The unique feature of the microbial system is that it enables self-healing of concrete. The effectiveness of microbially induced calcium carbonate precipitation (MICCP) in improving durability of cementitious building materials, restoration of stone monuments and soil bioclogging is discussed. Main emphasis has been laid on the potential of bacteria-based crack repair in concrete structure and the applications of different bacterial treatments to self-healing cracks. Furthermore, recommendations to employ the MICCP technology at commercial scale and reduction in the cost of application are provided in this review.

Flexible and Self-Healing Aqueous Supercapacitors for Low Temperature Applications: Polyampholyte Gel Electrolytes with Biochar Electrodes.

Science.gov (United States)

Li, Xinda; Liu, Li; Wang, Xianzong; Ok, Yong Sik; Elliott, Janet A W; Chang, Scott X; Chung, Hyun-Joong

2017-05-10

A flexible and self-healing supercapacitor with high energy density in low temperature operation was fabricated using a combination of biochar-based composite electrodes and a polyampholyte hydrogel electrolyte. Polyampholytes, a novel class of tough hydrogel, provide self-healing ability and mechanical flexibility, as well as low temperature operation for the aqueous electrolyte. Biochar is a carbon material produced from the low-temperature pyrolysis of biological wastes; the incorporation of reduced graphene oxide conferred mechanical integrity and electrical conductivity and hence the electrodes are called biochar-reduced-graphene-oxide (BC-RGO) electrodes. The fabricated supercapacitor showed high energy density of 30 Wh/kg with ~90% capacitance retention after 5000 charge-discharge cycles at room temperature at a power density of 50 W/kg. At -30 °C, the supercapacitor exhibited an energy density of 10.5 Wh/kg at a power density of 500 W/kg. The mechanism of the low-temperature performance excellence is likely to be associated with the concept of non-freezable water near the hydrophilic polymer chains, which can motivate future researches on the phase behaviour of water near polyampholyte chains. We conclude that the combination of the BC-RGO electrode and the polyampholyte hydrogel electrolyte is promising for supercapacitors for flexible electronics and for low temperature environments.

Self-healing method as strategy to promote health and rehabilitation of people with multiple sclerosis in the context of occupational therapy

Directory of Open Access Journals (Sweden)

Paula Pozzi Pimentel

2017-09-01

Full Text Available Introduction: Multiple sclerosis is a neurological chronic disease with continuous and differentiated evolution, it demands body self-knowledge for better understanding of preserved capacities, gradual losses and repercussion in the performance of activities and social participation. Objective: To analyze the group experience of the application of physical techniques based on self-healing method for health promotion and rehabilitation of people with multiple sclerosis, developed by Occupational Therapy. Method: Documental qualitative research referring to written records and audio transcripts of group sessions. Data analysis used the Collective Subject Discourse method. Results: Ten adults with multiple sclerosis, with varying ages and disease times, participated in the therapeutic group. Five participants reported representations and experiences due to the disease and the effect of learning the physical techniques of self-sealing. The benefits include a greater body awareness, decreased symptoms, improved functional capacity and recognition of the need of body practice routine. Conclusion: The therapeutic use of self-healing method demonstrated its applicability to promote the health benefits, rehabilitation, according to health policies. Due to limited literature on the benefits of using the self-healing method indicates the development of new studies.

Self-shielding models of MICROX-2 code: Review and updates

International Nuclear Information System (INIS)

Hou, J.; Choi, H.; Ivanov, K.N.

2014-01-01

Highlights: • The MICROX-2 code has been improved to expand its application to advanced reactors. • New fine-group cross section libraries based on ENDF/B-VII have been generated. • Resonance self-shielding and spatial self-shielding models have been improved. • The improvements were assessed by a series of benchmark calculations against MCNPX. - Abstract: The MICROX-2 is a transport theory code that solves for the neutron slowing-down and thermalization equations of a two-region lattice cell. The MICROX-2 code has been updated to expand its application to advanced reactor concepts and fuel cycle simulations, including generation of new fine-group cross section libraries based on ENDF/B-VII. In continuation of previous work, the MICROX-2 methods are reviewed and updated in this study, focusing on its resonance self-shielding and spatial self-shielding models for neutron spectrum calculations. The improvement of self-shielding method was assessed by a series of benchmark calculations against the Monte Carlo code, using homogeneous and heterogeneous pin cell models. The results have shown that the implementation of the updated self-shielding models is correct and the accuracy of physics calculation is improved. Compared to the existing models, the updates reduced the prediction error of the infinite multiplication factor by ∼0.1% and ∼0.2% for the homogeneous and heterogeneous pin cell models, respectively, considered in this study

Holistic nurses' stories of personal healing.

Science.gov (United States)

Smith, Marlaine C; Zahourek, Rothlyn; Hines, Mary Enzman; Engebretson, Joan; Wardell, Diane Wind

2013-09-01

The purpose of this study was to uncover the nature, experiences, and meaning of personal healing for holistic nurses through their narrative accounts. The study employed a qualitative descriptive design with methods of narrative and story inquiry. Participants were nurse attendees at an American Holistic Nurses' Association conference who volunteered for the study. They were invited to share a story about healing self or another. Twenty-five stories were collected; seven were about personal healing, and these are the focus of this analysis. Data were analyzed using a hybrid approach from narrative and story inquiry methods. Eleven themes were clustered under three story segments. The themes within the Call to the Healing Encounter are the following: recognition of the need to resolve a personal or health crisis, knowledge of or engagement in self-care practices, and reliance on intuitive knowing. Themes under the Experience of Healing are the following: connections; profound sensations, perceptions, and events; awareness of the reciprocal nature of healing; inner resolution: forgiveness, awakening, and acceptance; use of multiple holistic approaches; and witnessing manifestations of healing. The themes for Insights are the following: gratitude and appreciation and ongoing journey. A metastory synthesizing the themes is presented, and findings are related to existing literature on healing.

Multifunctional Hydrogel with Good Structure Integrity, Self-Healing, and Tissue-Adhesive Property Formed by Combining Diels-Alder Click Reaction and Acylhydrazone Bond.

Science.gov (United States)

Yu, Feng; Cao, Xiaodong; Du, Jie; Wang, Gang; Chen, Xiaofeng

2015-11-04

Hydrogel, as a good cartilage tissue-engineered scaffold, not only has to possess robust mechanical property but also has to have an intrinsic self-healing property to integrate itself or the surrounding host cartilage. In this work a double cross-linked network (DN) was designed and prepared by combining Diels-Alder click reaction and acylhydrazone bond. The DA reaction maintained the hydrogel's structural integrity and mechanical strength in physiological environment, while the dynamic covalent acylhydrazone bond resulted in hydrogel's self-healing property and controlled the on-off switch of network cross-link density. At the same time, the aldehyde groups contained in hydrogel further promote good integration of the hydrogel to surrounding tissue based on aldehyde-amine Schiff-base reaction. This kind of hydrogel has good structural integrity, autonomous self-healing, and tissue-adhesive property and simultaneously will have a good application in tissue engineering and tissue repair field.

Study of transfers and their interactions with self-healing in the cracks to increase the service life of infrastructures (bridges, nuclear centrals)

International Nuclear Information System (INIS)

Ismail, M.

2006-04-01

Concrete structures are frequently cracked by the action of different types of physicochemical mechanisms (external loads, restrained shrinkage, internal expansion). Cracks could impair the durability of concrete structures by creating preferential paths for the penetration of various types of potentially aggressive agents (liquids, gases, and ions). The aim of this thesis is to study transport properties in mechanically induced cracks. The first objective of the study is to better understand the potential effect of critical crack opening and self-healing. Cracks were generated in an inert material (brick) and in old mortar samples of 28 days and 2 years of age. A mechanical expansive core was used to generate cracks of constant width across the thickness of the sample. For the brick material, results show that a mechanical interaction between the fracture surfaces (critical crack opening) can affect the chloride-diffusion process along a crack path. A critical crack opening was also found for mortar samples. The age at which cracks were generated is also an important parameter. Self-healing was found to be more important in young mortars (28 days). The second objective of this thesis is the prediction of airflow in cracked cementitious material samples. A model proposed by Rizkalla et al. was evaluated through the experimental measurement of the flow coefficient n and the friction coefficient k. A simplified model was proposed to predict airflow through a crack for laminar type flow. The third research objective is to study the effect of self-healing on airflow through cracked mortar samples stored in a 100% relative humidity environment. Results show that self-healing mainly occurs during the first two months of storage. SEM analysis of fracture surfaces shows the formation of self-healing products such as calcite, C-S-H, and ettringite. (author)

Health Education Assistance Loan (HEAL) Program. Final rule.

Science.gov (United States)

2017-11-15

On July 1, 2014, the HEAL Program was transferred from the U.S. Department of Health and Human Services (HHS) to the U.S. Department of Education (the Department). To reflect this transfer and to facilitate the servicing of all HEAL loans that are currently held by the Department, the Secretary adds the HEAL Program regulations to the Department's chapter in the Code of Federal Regulations (CFR).

Improving the self-healing properties of concrete materials by using composite actions with fiber reinforced polymers.

Science.gov (United States)

2013-06-01

This research study is motivated by the need to reduce the costs of maintenance and repair of the aging transportation infrastructure in the US. The proposed approach is to use self-healing concrete. The objectives of this study were: (1) to evaluate...

Morphing Metal and Elastomer Bicontinuous Foams for Reversible Stiffness, Shape Memory, and Self-Healing Soft Machines.

Science.gov (United States)

Van Meerbeek, Ilse M; Mac Murray, Benjamin C; Kim, Jae Woo; Robinson, Sanlin S; Zou, Perry X; Silberstein, Meredith N; Shepherd, Robert F

2016-04-13

A metal-elastomer-foam composite that varies in stiffness, that can change shape and store shape memory, that self-heals, and that welds into monolithic structures from smaller components is presented. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Injectable self-healing carboxymethyl chitosan-zinc supramolecular hydrogels and their antibacterial activity.

Science.gov (United States)

Wahid, Fazli; Zhou, Ya-Ning; Wang, Hai-Song; Wan, Tong; Zhong, Cheng; Chu, Li-Qiang

2018-04-07

Injectable and self-healing hydrogels have found numerous applications in drug delivery, tissue engineering and 3D cell culture. Herein, we report an injectable self-healing carboxymethyl chitosan (CMCh) supramolecular hydrogels cross-linked by zinc ions (Zn 2+ ). Supramolecular hydrogels were obtained by simple addition of metal ions solution to CMCh solution at an appropriate pH value. The mechanical properties of these hydrogels were adjustable by the concentration of Zn 2+ . For example, the hydrogel with the highest concentration of Zn 2+ (CMCh-Zn4) showed strongest mechanical properties (storage modulus~11,000Pa) while hydrogel with the lowest concentration of Zn 2+ (CMCh-Zn1) showed weakest mechanical properties (storage modulus~220Pa). As observed visually and confirmed rheologically, the CMCh-Zn1 hydrogel with the lowest Zn 2+ concentration showed thixotropic property. CMCh-Zn1 hydrogel also presented injectable property. Moreover, the antibacterial properties of the prepared supramolecular hydrogels were studied against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) by agar well diffusion method. The results revealed Zn 2+ dependent antibacterial properties against both kinds of strains. The inhibition zones were ranging from ~11-24mm and ~10-22mm against S. aureus and E. coli, respectively. We believe that the prepared supramolecular hydrogels could be used as a potential candidate in biomedical fields. Copyright © 2018 Elsevier B.V. All rights reserved.

Wave-optics description of self-healing mechanism in Bessel beams.

Science.gov (United States)

Aiello, Andrea; Agarwal, Girish S

2014-12-15

Bessel beams' great importance in optics lies in that these propagate without spreading and can reconstruct themselves behind an obstruction placed across their path. However, a rigorous wave-optics explanation of the latter property is missing. In this work, we study the reconstruction mechanism by means of a wave-optics description. We obtain expressions for the minimum distance beyond the obstruction at which the beam reconstructs itself, which are in close agreement with the traditional one determined from geometrical optics. Our results show that the physics underlying the self-healing mechanism can be entirely explained in terms of the propagation of plane waves with radial wave vectors lying on a ring.

Piezoelectric and mechanical properties of fatigue resistant, self-healing PZT–ionomer composites

International Nuclear Information System (INIS)

James, N K; Lafont, U; Van der Zwaag, S; Groen, W A

2014-01-01

Piezoelectric ceramic–polymer composites with 0–3 connectivity were fabricated using lead zirconium titanate (PZT) powder dispersed in an ionomer (Zn ionomer) and its reference ethylene methacrylic acid copolymer (EMAA) polymer matrix. The PZT–Zn ionomer and PZT–EMAA composites were prepared by melt extrusion followed by hot pressing. The effects of poling conditions such as temperature, time and electric field on the piezoelectric properties of the composites were investigated. The experimentally observed piezoelectric charge coefficient and dielectric constant of the composites were compared with theoretical models. The results show that PZT–Zn ionomer composites have better piezoelectric properties compared to PZT–EMAA composites. The static and fatigue properties of the composites were investigated. The PZT–Zn ionomer composites were found to have excellent fatigue resistance even at strain levels of 4%. Due to the self-healing capabilities of the ionomer matrix, the loss of piezoelectric properties after high strain tensile cyclic loading could be partially recovered by thermal healing. (paper)

Piezoelectric and mechanical properties of fatigue resistant, self-healing PZT-ionomer composites

Science.gov (United States)

James, N. K.; Lafont, U.; van der Zwaag, S.; Groen, W. A.

2014-05-01

Piezoelectric ceramic-polymer composites with 0-3 connectivity were fabricated using lead zirconium titanate (PZT) powder dispersed in an ionomer (Zn ionomer) and its reference ethylene methacrylic acid copolymer (EMAA) polymer matrix. The PZT-Zn ionomer and PZT-EMAA composites were prepared by melt extrusion followed by hot pressing. The effects of poling conditions such as temperature, time and electric field on the piezoelectric properties of the composites were investigated. The experimentally observed piezoelectric charge coefficient and dielectric constant of the composites were compared with theoretical models. The results show that PZT-Zn ionomer composites have better piezoelectric properties compared to PZT-EMAA composites. The static and fatigue properties of the composites were investigated. The PZT-Zn ionomer composites were found to have excellent fatigue resistance even at strain levels of 4%. Due to the self-healing capabilities of the ionomer matrix, the loss of piezoelectric properties after high strain tensile cyclic loading could be partially recovered by thermal healing.

New extremal binary self-dual codes of lengths 64 and 66 from bicubic planar graphs

OpenAIRE

Kaya, Abidin

2016-01-01

In this work, connected cubic planar bipartite graphs and related binary self-dual codes are studied. Binary self-dual codes of length 16 are obtained by face-vertex incidence matrices of these graphs. By considering their lifts to the ring R_2 new extremal binary self-dual codes of lengths 64 are constructed as Gray images. More precisely, we construct 15 new codes of length 64. Moreover, 10 new codes of length 66 were obtained by applying a building-up construction to the binary codes. Code...

Contributions of hard and soft blocks in the self-healing of metal-ligand-containing block copolymers

NARCIS (Netherlands)

Bose, Ranjita K.; Enke, Marcel; Grande, Antonio M.; Zechel, Stefan; Schacher, Felix H.; Hager, Martin D.; Garcia, Santiago J.; Schubert, Ulrich S.; van der Zwaag, Sybrand

2017-01-01

The main aim of this work is to study the respective contribution of the hard and soft blocks of a metal-ligand containing block copolymer to the self-healing behavior. To this aim, different block copolymers containing terpyridine were synthesized using reversible addition-fragmentation chain

Hydrophobic Light-to-Heat Conversion Membranes with Self-Healing Ability for Interfacial Solar Heating

KAUST Repository

Zhang, Lianbin

2015-07-01

Self-healing hydrophobic light-to-heat conversion membranes for interfacial solar heating are fabricated by deposition of light-to-heat conversion material of polypyrrole onto porous stainless steel mesh, followed by hydrophobic fluoroalkylsilane modification. The mesh-based membranes spontaneously stay at the water–air interface, collect and convert solar light into heat, and locally heat only the water surface for an enhanced evaporation.

Hydrophobic Light-to-Heat Conversion Membranes with Self-Healing Ability for Interfacial Solar Heating

KAUST Repository

Zhang, Lianbin; Tang, Bo; Wu, Jinbo; Li, Renyuan; Wang, Peng

2015-01-01

Self-healing hydrophobic light-to-heat conversion membranes for interfacial solar heating are fabricated by deposition of light-to-heat conversion material of polypyrrole onto porous stainless steel mesh, followed by hydrophobic fluoroalkylsilane modification. The mesh-based membranes spontaneously stay at the water–air interface, collect and convert solar light into heat, and locally heat only the water surface for an enhanced evaporation.

Development of plant dynamic analysis code for integrated self-pressurized water reactor (ISPDYN), and comparative study of pressure control methods

International Nuclear Information System (INIS)

Kusunoki, Tsuyoshi; Yokomura, Takeyoshi; Nabeshima, Kunihiko; Shimazaki, Junya; Shinohara, Yoshikuni.

1988-01-01

This report describes the development of plant dynamic analysis code (ISPDYN) for integrated self-pressurized water reactor, and comparative study of pressure control methods with this code. ISPDYN is developed for integrated self-pressurized water reactor, one of the trial design by JAERI. In the transient responses, the calculated results by ISPDYN are in good agreement with the DRUCK calculations. In addition, this report presents some sensitivity studies for selected cases. Computing time of this code is very short so as about one fifth of real time. The comparative study of self-pressurized system with forced-pressurized system by this code, for rapid load decrease and increase cases, has provided useful informations. (author)

Polymer-Cement Composites with Self-Healing Ability for Geothermal and Fossil Energy Applications

Energy Technology Data Exchange (ETDEWEB)

Childers, M. Ian; Nguyen, Manh-Thuong; Rod, Kenton A.; Koech, Phillip K.; Um, Wooyong; Chun, Jaehun; Glezakou, Vassiliki-Alexandra; Linn, Diana; Roosendaal, Timothy J.; Wietsma, Thomas W.; Huerta, Nicolas John; Kutchko, Barbara G.; Fernandez, Carlos A.

2017-05-18

Sealing of wellbores in geothermal and tight oil/gas reservoirs by filling the annulus with cement is a well-established practice. Failure of the cement as a result of physical and/or chemical stress is a common problem with serious environmental and financial consequences. Numerous alternative cement blends have been proposed for the oil and gas industry. Most of these possess poor mechanical properties, or are not designed to work in high temperature environments. This work reports on a novel polymer-cement composite with remarkable self-healing ability that maintains the required properties of typical wellbore cements and may be stable at most geothermal temperatures. We combine for the first time experimental analysis of physical and chemical properties with density functional theory simulations to evaluate cement performance. The thermal stability and mechanical strength are attributed to the formation of a number of chemical interactions between the polymer and cement matrix including covalent bonds, hydrogen bonding, and van der Waals interactions. Self-healing was demonstrated by sealing fractures with 0.3–0.5 mm apertures, 2 orders of magnitude larger than typical wellbore fractures. This polymer-cement composite represents a major advance in wellbore cementing that could improve the environmental safety and economics of enhanced geothermal energy and tight oil/gas production.

On the use of crystalline admixtures in cement based construction materials: from porosity reducers to promoters of self healing

Science.gov (United States)

Ferrara, Liberato; Krelani, Visar; Moretti, Fabio

2016-08-01

The project detailed in this paper aims at a thorough characterization of the effects of crystalline admixtures, currently employed as porosity reducing admixtures, on the self-healing capacity of the cementitious composites, i.e. their capacity to completely or partially re-seal cracks and, in case, also exhibit recovery of mechanical properties. The problem has been investigated with reference to both a normal strength concrete (NSC) and a high performance fibre reinforced cementitious composite (HPFRCC). In the latter case, the influence of flow-induced fibre alignment has also been considered in the experimental investigation. With reference to either 3-point (for NSC) or 4-point (for HPFRCC) bending tests performed up to controlled crack opening and up to failure, respectively before and after exposure/conditioning recovery of stiffness and stress bearing capacity has been evaluated to assess the self-healing capacity. In a durability-based design framework, self-healing indices to quantify the recovery of mechanical properties will also be defined. In NSC, crystalline admixtures are able to promote up to 60% of crack sealing even under exposure to open air. In the case of HPFRCCs, which would already feature autogenous healing capacity because of their peculiar mix compositions, the synergy between the dispersed fibre reinforcement and the action of the crystalline admixture has resulted in a likely ‘chemical pre-stressing’ of the same reinforcement, from which the recovery of mechanical performance of the material has greatly benefited, up to levels even higher than the performance of the virgin un-cracked material.

Field application of self-healing concrete with natural fibres as linings for irrigation canals in Ecuador

NARCIS (Netherlands)

Sierra Beltran, M.G.; Jonkers, H.M.; Mors, R.M.; Mera-Ortiz, W.

2015-01-01

This paper describes the first field application of self-healing concrete with alkaliphilic spore-forming bacteria and reinforced with natural fibres. The application took place in the highlands in Ecuador in July 2014. The concrete was cast as linings for an irrigation canal that transports water

Contributions of hard and soft blocks in the self-healing of metal-ligand-containing block copolymers

NARCIS (Netherlands)

Bose, R.K.; Enke, Marcel; Grande, A.M.; Zechel, Stefan; Schacher, Felix H.; Hager, Martin D.; Garcia Espallargas, Santiago J.; Schubert, Ulrich S.; van der Zwaag, S.

2017-01-01

The main aim of this work is to study the respective contribution of the hard and soft blocks of a metal-ligand containing block copolymer to the self-healing behavior. To this aim, different block copolymers containing terpyridine were synthesized using reversible addition-fragmentation chain

An adaptive self-healing ionic liquid nanocomposite membrane for olefin-paraffin separations.

Science.gov (United States)

Pitsch, Fee; Krull, Florian F; Agel, Friederike; Schulz, Peter; Wasserscheid, Peter; Melin, Thomas; Wessling, Matthias

2012-08-16

An adaptive self-healing ionic liquid nanocomposite membrane comprising a multi-layer support structure hosting the ionic salt [Ag](+) [Tf(2) N](-) is used for the separation of the olefin propylene and the paraffin propane. The ionic salt renders liquid like upon complexation with propylene, resulting in facilitated transport of propylene over propane at benchmark-setting selectivity and permeance levels. The contacting with acetylene causes the ionic salt to liquefy without showing evidence of forming explosive silver acetylide. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhancement of crack healing efficiency and performance of SAP in biocrete

Science.gov (United States)

Giriselvam, M. G.; Poornima, V.; Venkatasubramani, R.; Sreevidya, V.

2018-02-01

Concrete usage in Construction becomes more common in this speedy world. Despite its benefits, concrete often exhibits crack which appear due to stresses. Larger cracks cause Structural integrity problems and smaller cracks may result in durability issues. A novel environmental friendly strategy to restore or remediate cracks formed in the structures is bio-mineralization of calcium carbonate using microbes such as Bacillus Subtilis (used in this study), as manual repair and maintenance is costly. In this Paper, an idea of using Super Absorbent Polymer in Bacterial Concrete was analysed which increases the strength and durability properties of concrete and also which acts as a protection to bacteria, where Self-Healing nature is viewed. In the span of 90 days, the results of Bacterial concrete cured under normal water providing nutrients inside with SAP shows healing up to 74 % and without SAP displays 49 % and when it is cured under nutrient medium, Bacterial Concrete having SAP displays healing up to 66 %, whereas without SAP it displays 57.4% of healing. During the observation it is discernible that the crack width ranging from 0.10 mm near 0.45 mm show better self-healing capacity. XRD analysis displays the presence of Calcium carbonate precipitation in cracks.

Dynamic Self-Healing Mechanism for Transactional Business Process

Directory of Open Access Journals (Sweden)

Yuhai Zhao

2015-01-01

Full Text Available It is clear that transactional behavior consistency is a prerequisite and basis for construction of a reliable services-based business application. However, in previous works, maintaining transactional consistency during exception handling was ignored. Maintaining transactional consistency requires functionality for rolling back some operations and revoking uploaded data. Replacing only the failed service will eventually lead to overall business application failure. In this study, we take fully into account the behavioral consistency of transactional services and propose two effective self-healing mechanisms for service-based applications. If a service enters into potential failure condition, a rescheduling mechanism is triggered to maintain consistent transactional behavior and to ensure reliable execution; if a service fails during execution, the compensation operation is triggered and the system will take action to ensure transactional behavior consistency. Meanwhile, cost-benefit analysis with compensation support is proposed to minimize the dynamic reselection cost. Finally, the experimental analysis shows that the proposed strategies can effectively guarantee the reliability of Web-based applications system.

Self-orthogonal codes from some bush-type Hadamard matrices ...

African Journals Online (AJOL)

By means of a construction method outlined by Harada and Tonchev, we determine some non-binary self-orthogonal codes obtained from the row span of orbit matrices of Bush-type Hadamard matrices that admit a xed-point-free and xed-block-free automorphism of prime order. We show that the code [20; 15; 4]5 obtained ...

A suicidal recovery theory to guide individuals on their healing and recovering process following a suicide attempt.

Science.gov (United States)

Sun, Fan-Ko; Long, Ann

2013-09-01

To develop a theory to guide the recovery process of a recent suicide attempt. Suicide is one of the 10 leading causes of death in many countries. Many nations have set targets to reduce the high incidence of suicide by aiming to prevent people from taking their own lives and also providing care to promote the healing of those who attempt suicide. A qualitative grounded theory approach was used. Data were collected in 2011-2012 in a Taiwanese hospital until data saturation occurred. Twenty participants were interviewed, comprising patients who recovered from suicide attempts (N = 14) and their caregivers (N = 6). Data were analysed using open, axial, and selective coding and using the constant comparison technique. A substantive theory was formulated to guide the recovery process of people who have recently attempted suicide. The core category that emerged from the data collected was 'Striving to accept the value of self-in-existence'. Other key categories linked to and embraced in this core category were: becoming flexible and open-minded, re-building a positive sense of self, and endeavouring to live a peaceful and contented life. Nurses could use this theory as a theoretical framework to guide people who are recovering from a suicide attempt by affording them the opportunity to grow and heal, and facilitating the re-building a positive sense of self, acknowledging the uncertainties of life, and inspiring hope. © 2013 Blackwell Publishing Ltd.

Self-Healing Structural Materials for Damage Tolerant Aerospace Vehicles: Mechanoresponsive healing polymers

Data.gov (United States)

National Aeronautics and Space Administration — Materials that are capable of puncture healing upon impact show great promise for space exploration applications wherein an internal breach caused by micrometeoroid...

Current challenges and future directions for bacterial self-healing concrete.

Science.gov (United States)

Lee, Yun Suk; Park, Woojun

2018-04-01

Microbially induced calcium carbonate precipitation (MICP) has been widely explored and applied in the field of environmental engineering over the last decade. Calcium carbonate is naturally precipitated as a byproduct of various microbial metabolic activities. This biological process was brought into practical use to restore construction materials, strengthen and remediate soil, and sequester carbon. MICP has also been extensively examined for applications in self-healing concrete. Biogenic crack repair helps mitigate the high maintenance costs of concrete in an eco-friendly manner. In this process, calcium carbonate precipitation (CCP)-capable bacteria and nutrients are embedded inside the concrete. These bacteria are expected to increase the durability of the concrete by precipitating calcium carbonate in situ to heal cracks that develop in the concrete. However, several challenges exist with respect to embedding such bacteria; harsh conditions in concrete matrices are unsuitable for bacterial life, including high alkalinity (pH up to 13), high temperatures during manufacturing processes, and limited oxygen supply. Additionally, many biological factors, including the optimum conditions for MICP, the molecular mechanisms involved in MICP, the specific microorganisms suitable for application in concrete, the survival characteristics of the microorganisms embedded in concrete, and the amount of MICP in concrete, remain unclear. In this paper, metabolic pathways that result in conditions favorable for calcium carbonate precipitation, current and potential applications in concrete, and the remaining biological challenges are reviewed.

Biomimetic Self-Organization and Self-Healing

DEFF Research Database (Denmark)

Lenau, Torben Anker; Hesselberg, Thomas

2013-01-01

of the important role of biophysics. Some physical applications include adhesion superhydrophobicity and self-cleaning, structural coloration, photonic devices, biomaterials and composite materials, sensor systems, robotics and locomotion, and ultra-lightweight structures. Explores biomimicry, a fast...... and vision sensors, Engineered Biomimicry explores a wide range of technologies informed by living natural systems. Engineered Biomimicry helps physicists, engineers and material scientists seek solutions in nature to the most pressing technical problems of our times, while providing a solid understanding...

Soft decoding a self-dual (48, 24; 12) code

Science.gov (United States)

Solomon, G.

1993-01-01

A self-dual (48,24;12) code comes from restricting a binary cyclic (63,18;36) code to a 6 x 7 matrix, adding an eighth all-zero column, and then adjoining six dimensions to this extended 6 x 8 matrix. These six dimensions are generated by linear combinations of row permutations of a 6 x 8 matrix of weight 12, whose sums of rows and columns add to one. A soft decoding using these properties and approximating maximum likelihood is presented here. This is preliminary to a possible soft decoding of the box (72,36;15) code that promises a 7.7-dB theoretical coding under maximum likelihood.

ARC Code TI: Self-Healing Independent File Transfer (Shift)

Data.gov (United States)

National Aeronautics and Space Administration — Shift is a lightweight framework for high performance local and remote file transfers that provides resiliency across a wide variety of failure scenarios through...

Novel antifouling self-healing poly(carboxybetaine methacrylamide-co-HEMA) nanocomposite hydrogels with superior mechanical properties

Czech Academy of Sciences Publication Activity Database

Kostina, Nina Yu.; Sharifi, S.; de los Santos Pereira, Andres; Michálek, Jiří; Grijpma, D. W.; Rodriguez-Emmenegger, Cesar

2013-01-01

Roč. 1, č. 41 (2013), s. 5644-5650 ISSN 2050-750X R&D Projects: GA AV ČR KAN200520804; GA ČR GA13-00939S; GA ČR GAP205/12/1702; GA ČR GAP106/12/1451; GA ČR GBP205/12/G118 Institutional support: RVO:61389013 Keywords : hydrogels * self- healing * antifouling Subject RIV: CD - Macromolecular Chemistry

Expert advice provided through telemedicine improves healing of chronic wounds: prospective cluster controlled study.

Science.gov (United States)

Zarchi, Kian; Haugaard, Vibeke B; Dufour, Deirdre N; Jemec, Gregor B E

2015-03-01

Telemedicine is widely considered as an efficient approach to manage the growing problem of chronic wounds. However, to date, there is no convincing evidence to support the clinical efficacy of telemedicine in wound management. In this prospective cluster controlled study, we tested the hypothesis that advice on wound management provided by a team of wound-care specialists through telemedicine would significantly improve the likelihood of wound healing compared with the best available conventional practice. A total of 90 chronic wound patients in home care met all study criteria and were included: 50 in the telemedicine group and 40 in the conventional group. Patients with pressure ulcers, surgical wounds, and cancer wounds were excluded. During the 1-year follow-up, complete wound healing was achieved in 35 patients (70%) in the telemedicine group compared with 18 patients (45%) in the conventional group. After adjusting for important covariates, offering advice on wound management through telemedicine was associated with significantly increased healing compared with the best available conventional practice (telemedicine vs. conventional practice: adjusted hazard ratio 2.19; 95% confidence interval: 1.15-4.17; P=0.017). This study strongly supports the use of telemedicine to connect home-care nurses to a team of wound experts in order to improve the management of chronic wounds.

Scanning electron microscopy of the collodion membrane from a self-healing collodion baby*

Science.gov (United States)

de Almeida Jr., Hiram Larangeira; Isaacsson, Henrique; Guarenti, Isabelle Maffei; Silva, Ricardo Marques e; de Castro, Luis Antônio Suita

2015-01-01

Abstract Self-healing collodion baby is a well-established subtype of this condition. We examined a male newborn, who was covered by a collodion membrane. The shed membrane was examined with scanning electron microscopy. The outer surface showed a very compact keratin without the normal elimination of corneocytes. The lateral view of the specimen revealed a very thick, horny layer. The inner surface showed the structure of lower corneocytes with polygonal contour. With higher magnifications villous projections were seen in the cell membrane. PMID:26375232

Simulation-Aided Design of Tubular Polymeric Capsules for Self-Healing Concrete

Science.gov (United States)

Šavija, Branko; Feiteira, João; Araújo, Maria; Chatrabhuti, Sutima; Raquez, Jean-Marie; Van Tittelboom, Kim; Gruyaert, Elke; De Belie, Nele; Schlangen, Erik

2016-01-01

Polymeric capsules can have an advantage over glass capsules used up to now as proof-of-concept carriers in self-healing concrete. They allow easier processing and afford the possibility to fine tune their mechanical properties. Out of the multiple requirements for capsules used in this context, the capability of rupturing when crossed by a crack in concrete of a typical size is one of the most relevant, as without it no healing agent is released into the crack. This study assessed the fitness of five types of polymeric capsules to fulfill this requirement by using a numerical model to screen the best performing ones and verifying their fitness with experimental methods. Capsules made of a specific type of poly(methyl methacrylate) (PMMA) were considered fit for the intended application, rupturing at average crack sizes of 69 and 128 μm, respectively for a wall thickness of ~0.3 and ~0.7 mm. Thicker walls were considered unfit, as they ruptured for crack sizes much higher than 100 μm. Other types of PMMA used and polylactic acid were equally unfit for the same reason. There was overall good fitting between model output and experimental results and an elongation at break of 1.5% is recommended regarding polymers for this application. PMID:28772370

Intentionality and hatha yoga: an exploration of the theory of intentionality, the matrix of healing--a growth model.

Science.gov (United States)

Deary, Lauri; Roche, Joan; Plotkin, Karen; Zahourek, Rothlyn

2011-01-01

Hatha yoga increases self-awareness and well-being. Intentionality is creating motivation and then action. This qualitative study explored intentionality during hatha yoga sessions using narrative analysis. The results supported and expanded Zahourek's theory of intentionality, the matrix of healing, and provide new insights into intentionality in healing.

Integration of the Self-Healing eDNA Architecture in a Liquid Crystal Waveguide-based Fourier Transform Spectrometer

DEFF Research Database (Denmark)

Boesen, Michael Reibel; Keymeulen, D.; Madsen, Jan

2011-01-01

In this work we describe the first real world case study for the self-healing eDNA (electronic DNA) architecture by implementing the control and data processing of a Fourier Transform Spectrometer (FTS) on an eDNA prototype. For this purpose the eDNA prototype has been ported from a Xilinx Virtex 5...

Degradation failure model of self-healing metallized film pulse capacitor

International Nuclear Information System (INIS)

Sun Quan; Zhong Zheng; Zhou Jinglun; Zhao Jianyin; Wei Xiaofeng; Guo Liangfu; Zhou Pizhang; Li Yizheng; Chen Dehuai

2004-01-01

The high energy density self-healing metallized film pulse capacitor has been applied to all kinds of laser facilities for their power conditioning systems, whose reliability and expense are straightforwardly affected by the reliability level of the capacitors. Based on the related research in literature, this paper analyses the degradation mechanism of the capacitor, and presents a new degradation failure model--the Gauss-Poisson model. The Gauss-Poisson model divides degradation of capacitor into naturalness degradation and outburst one. Compared with traditional Weibull failure model, the new model is more precise in evaluating the lifetime of the capacitor, and the life tests for this model are simple in design, and lower in the cost of time or expense. The Gauss-Poisson model will be a fine and widely used degradation disable model. (author)

Effect of healing touch training on self-care awareness in nurses

Science.gov (United States)

Black, Pegi

Nursing focuses on supporting clients' health and health behaviors; however, they tend to exhibit unproductive behaviors when it comes to caring for themselves. As nurses' self-neglect can undermine client care, supporting nurses' self-care practices are expected to translate into clients' self-care. Healing Touch (HT) is one option for supporting nurses' self-care, as it is an accepted nursing practice and studies suggest that HT may have beneficial effects for those delivering it. This study examined the impact of a 2-day HT training on awareness of the need for self-care in nurses. HT training was offered as continuing education for 45 nurses at a Veteran's Administration hospital in Long Beach, CA. This mixed-methods study used a pre/post-test design to measure the effects of HT Level 1 training on nurses' self-care self-awareness. Independent samples t-tests and analyses of variance were used to detect whether any significant differences emerged based on participant demographic data. Data were analyzed using paired t-tests to determine whether participants' self-awareness changed over the study period. Effect size for any differences were calculated using Cohen's d. Open-ended responses were reviewed and common themes were identified related to what participants believed they learned and how it affected their care for themselves and their clients. Two increases were found to be significant and of sufficient power when comparing pre- to delayed post-test scores: physical self-care awareness (mean difference = 0.956, t(44) = 5.085, p = .000, r = .61) and professional self-care awareness (mean difference = .955, t(43) = 5.277, p = .000, r = .63). Qualitative findings suggested that changes in their awareness, self-directed practices, and patient care practices are anticipated, evident, and sustained based upon themes across the three tests. Nurses are advised to take a course that teaches specific self-care techniques and strategies and continue practicing

Holistic nurses' stories of healing of another.

Science.gov (United States)

Enzman Hines, Mary; Wardell, Diane Wind; Engebretson, Joan; Zahourek, Rothlyn; Smith, Marlaine C

2015-03-01

The purpose of this study was to uncover the essence and meaning of healing through narrative accounts of holistic nurses, using a qualitative, descriptive design integrating narrative and story inquiry. Twenty-five stories were collected. Seven stories revealed personal healing and have been published in a prior article. Eighteen stories, the focus of this analysis, revealed healing of another. A hybrid method blending narrative and story guided the overall process for the study. Nine themes emerged describing healing of another within three story segments: The Call to Healing, The Experience of Healing, and Insights. The theme within The Call to the Healing Encounter was Drawn by Compassion to the Vulnerability and/or Suffering of Another. Five themes describe the Experience of Healing: Connection: Cocreating Relationships; Taking Risks and Dealing With Skeptical Colleagues; Use of Modalities and Actions as Tools in Developing Self as an Instrument of Healing; Profound, Ineffable Events; and Using Metaphor and Rituals to Describe Healing. Three themes describe Insights: Mutual Transformation, Change, and Reciprocity; Gratitude for the Healing Encounter; and Leaving a Legacy. The metastory, a reconstructed story created by the researchers, was the final phase of research synthesizing and demonstrating themes of healing of another. Results were compared to existing healing literature. © The Author(s) 2014.

Synthesis of a Self-Healing Polymer Based on Reversible Diels-Alder Reaction: An Advanced Undergraduate Laboratory at the Interface of Organic Chemistry and Materials Science

Science.gov (United States)

Weizman, Haim; Nielsen, Christian; Weizman, Or S.; Nemat-Nasser, Sia

2011-01-01

This laboratory experiment exposes students to the chemistry of self-healing polymers based on a Diels-Alder reaction. Students accomplish a multistep synthesis of a monomer building block and then polymerize it to form a cross-linked polymer. The healing capability of the polymer is verified by differential scanning calorimetry (DSC) experiments.…

Providing cost-effective treatment of hard-to-heal wounds in the community through use of NPWT.

Science.gov (United States)

Hampton, Jane

2015-06-01

The treatment of non-healing wounds accounts for a high proportion of wound care costs. Advanced technology treatments, such as negative pressure wound therapy (NPWT), could be cost-effective if they result in faster healing. The objective of this study is to assess the effect on healing and the cost-effectiveness of a single-use NPWT (i.e PICO by Smith & Nephew) when used on hard-to-heal wounds in a community setting. This was a cohort case study in which wounds were treated with NWPT for 2 weeks. Wounds were assessed every 2-4 weeks to a healed state. The weekly cost of treatment prior to intervention, that is, the products used and nurse time, were compared with treatment costs associated with NWPT and after a return to standard treatment. The study included 9 patients with leg ulcers or pressure ulcers that had been slow healing or non-healing for at least 6 weeks. While treated with NPWT, the average weekly reduction in wound size was 21%. The wound size achieved with NPWT was reached on average 10 weeks earlier than predicted. The increased healing rate continued after PICO stopped and 5 wounds healed on average 8 weeks later. Frequency of dressing changes fell from 4 times weekly at baseline to 2 times a week with NPWT and to 1.8 after NPWT stopped. Weekly cost of treatment with NPWT was, on average, 1.6 times higher than the baseline, but fell to 3 times less when NPWT stopped owing to the reduction in dressing changes. The amount of change in healing rate was considerably higher than the increase in costs associated with NPWT. NWPT is a cost-effective treatment for hard-to-heal wounds. Wounds decreased in size and healed more quickly under NWPT treatment than under standard treatment. Additional NPWT costs can be quickly offset by faster healing and a shortened treatment period.

Recent Advances in Thermoplastic Puncture-Healing Polymers

Science.gov (United States)

Bogert, Philip B.; Working, Dennis C.; Wise, Kristopher E.; Smith, Janice Y.; Topping, Crystal C.; Britton, Sean M.; Bagby, Paul R.; Siochi, Emilie J.

2010-01-01

The motivation for this work is to develop self-healing polymeric materials to enable damage tolerant systems, and to tailor puncture healing for use temperatures and applications. This will be a benefit in environments and conditions where access for manual repair is limited or impossible, or where damage may not be detected.

An assessment of meaning in life-threatening illness: development of the Healing Experience in All Life Stressors (HEALS).

Science.gov (United States)

Sloan, Danetta Hendricks; BrintzenhofeSzoc, Karlynn; Kichline, Tiffany; Baker, Karen; Pinzon, Jean-Paul; Tafe, Christina; Li, Lingsheng; Cheng, M Jennifer; Berger, Ann

2017-01-01

Patients with life-threatening or chronic illness report an experience of increased positive psychological, social, and/or spiritual change during diagnosis and/or treatment of their illness, even in the face of unfavorable prognosis. This transformation begins through the ability to make their life meaningful by forming meaningful connections that emerge through self-introspection and relationships with a divine entity, nature, and other people. The Healing Experience in All Life Stressors (HEALS) assessment provides a way to identify distress-causing changes that may interfere with the development of meaning and psycho-social-spiritual homeostasis. Preliminary examination of responses to items on the HEALS and examination of the factor structure. The 48-item HEALS questionnaire was developed using a multistep process: literature review for concept development, item generation from qualitative data, and face and content validity by expert panel. In the current study, HEALS was completed by 100 patients diagnosed with life-limiting disease and seen by the palliative care team at a large research institution in the US. Exploratory factor analysis techniques were used to determine scale structure of the instrument. Outcome testing of sample adequacy using Kaiser-Meyer-Olkin statistic was 0.75, which exceeds the recommended value of 0.60. The HEALS show very good internal consistency with a Cronbach's a of 0.94. Overall results of the exploratory factor analysis established a four-factor questionnaire: 1) religion; 2) spirituality, demonstrated by a) interaction with a religious community and b) belief in higher power; 3) intrapersonal; and 4) interpersonal relationships expressed through psychological changes resulting in enhanced outlook and improvement in relationships with family and friends. This study involved the initial step to commence the process of scale validation, with promising outcomes identifying subscales as an effective way to assess the construct of

Self-Healing Composite of Thermoset Polymer and Programmed Super Contraction Fibers

Science.gov (United States)

Li, Guoqiang (Inventor); Meng, Harper (Inventor)

2016-01-01

A composition comprising thermoset polymer, shape memory polymer to facilitate macro scale damage closure, and a thermoplastic polymer for molecular scale healing is disclosed; the composition has the ability to resolve structural defects by a bio-mimetic close-then heal process. In use, the shape memory polymer serves to bring surfaces of a structural defect into approximation, whereafter use of the thermoplastic polymer for molecular scale healing allowed for movement of the thermoplastic polymer into the defect and thus obtain molecular scale healing. The thermoplastic can be fibers, particles or spheres which are used by heating to a level at or above the thermoplastic's melting point, then cooling of the composition below the melting temperature of the thermoplastic. Compositions of the invention have the ability to not only close macroscopic defects, but also to do so repeatedly even if another wound/damage occurs in a previously healed/repaired area.

Factors Influencing Self Employment Media Service Providers ...

African Journals Online (AJOL)

Factors Influencing Self Employment Media Service Providers among Tertiary ... role stereotype and common business practices on media self employment in ... Sex, Psycho-social Characteristics, self Employment, Providing Media Services.

Self-Healing Capacity of Asphalt Mixtures Including By-Products Both as Aggregates and Heating Inductors.

Science.gov (United States)

Vila-Cortavitarte, Marta; Jato-Espino, Daniel; Castro-Fresno, Daniel; Calzada-Pérez, Miguel Á

2018-05-15

Major advances have been achieved in the field of self-healing by magnetic induction in which the addition of metallic particles into asphalt mixtures enables repairing their own cracks. This technology has already been proven to increase the life expectancy of roads. Nevertheless, its higher costs in comparison with conventional maintenance caused by the price of virgin metallic particles still makes it unattractive for investment. This research aimed at making this process economically accessible as well as environmentally efficient. To this end, an intense search for suitable industrial by-products to substitute both the virgin metal particles and the natural aggregates forming asphalt mixtures was conducted. The set of by-products used included sand blasting wastes, stainless shot wastes, and polished wastes as metallic particles and other inert by-products as aggregates. The results demonstrated that the by-products were adequately heated, which leads to satisfactory healing ratios in comparison with the reference mixture.

Robust Power Supply Restoration for Self-Healing Active Distribution Networks Considering the Availability of Distributed Generation

Directory of Open Access Journals (Sweden)

Qiang Yang

2018-01-01

Full Text Available The increasing penetration of distributed generations (DGs with intermittent and stochastic characteristics into current power distribution networks can lead to increased fault levels and degradation in network protection. As one of the key requirements of active network management (ANM, efficient power supply restoration solution to guarantee network self-healing capability with full consideration of DG uncertainties is demanded. This paper presents a joint power supply restoration through combining the DG local restoration and switcher operation-based restoration to enhance the self-healing capability in active distribution networks considering the availability of distributed generation. The restoration algorithmic solution is designed to be able to carry out power restoration in parallel upon multiple simultaneous faults to maximize the load restoration while additionally minimizing power loss, topology variation and power flow changes due to switcher operations. The performance of the proposed solution is validated based on a 53-bus distribution network with wind power generators through extensive simulation experiments for a range of fault cases and DG scenarios generated based on Heuristic Moment Matching (HMM method to fully consider the DG randomness. The numerical result in comparison with the existing solutions demonstrates the effectiveness of the proposed power supply restoration solution.

Modelling the influence of cracking and healing on modal properties of concrete beams

NARCIS (Netherlands)

Savija, B.; Schlangen, E.

2015-01-01

Concrete structures are commonly cracked when in service. To overcome issues arising from cracking, self-healing concrete is being developed. Together with the development of the material, techniques to verify and quantify self-healing are being developed. A number of destructive techniques have

Self-Healing anticorrosive coatings

DEFF Research Database (Denmark)

Nesterova, Tatyana

%. The number is lower than anticipated and needs to be confirmed. Finally, a 3-D model, based on Monte-Carlo simulations, has been developed for prediction of healing efficiency of a microcapsule-based anticorrosive coating. Two kinds of cracks were considered: cracks accommodated within the bulk coating...... associated with development and testing of this type of coating. A laboratory investigation, to identify the most suitable method for production of mechanically stable (filled with industrially relevant core materials) and forming a free-flowing powder upon drying microcapsules, has been performed. Four...... reduces the intensity of crack formation (both in number and length) compared to filler-containing coatings and prevents the coating from flaking upon damage. Based on specular gloss measurements, a preliminary critical pigment (microcapsule) concentration (CPVC) value was estimated to about 30 vol...

Characterization and kinetic study of Diels-Alder reaction: Detailed study on N-phenylmaleimide and furan based benzoxazine with potential self-healing application

Directory of Open Access Journals (Sweden)

Z. Stirn

2016-07-01

Full Text Available The Diels-Alder reaction between N-phenylmaleimide and benzoxazine bearing furan group was investigated for the purpose of successful appliance of self-healing in benzoxazine polymer networks. The reaction as a function of temperature/time was performed in molten state and in a solution, where also the kinetic study was performed. The Diels-Alder reaction leads to a mixture of two diastereomers: endo presented at lower cyclo-reversion temperature and exo at higher. Therefore, the conversion rates and exo/endo ratio were studied in detail for both systems. For instance, in molten state the Diels-Alder reaction was triggered by the temperature of the melting point at 60 °C with exo/endo ratio preferable to the endo adduct. The study of the kinetics in a solution revealed that the Diels-Alder reaction followed typical bimolecular reversible second-order reaction. The activation energies were close to the previous literature data; 48.4 and 51.9 kJ·mol–1 for Diels-Alder reaction, and 91.0 and 102.3 kJ·mol–1 for retro-Diels-Alder reaction, in acetonitrile and chloroform, respectively. The reaction equilibrium in a solution is much more affected by the retro-Diels-Alder reaction than in a molten state. This study shows detailed investigation of DA reaction and provides beneficial knowledge for further use in self-healing polymer networks.

A Building Brick Principle to Create Transparent Composite Films with Multicolor Emission and Self-Healing Function.

Science.gov (United States)

Xiong, Yuan; Zhu, Minshen; Wang, Zhenguang; Schneider, Julian; Huang, He; Kershaw, Stephen V; Zhi, Chunyi; Rogach, Andrey L

2018-05-01

A cellulose paper is used impregnated with light-emitting CdTe nanocrystals and carbon dots, and filled with a polyurethane to fabricate uniform transparent composite films with bright photoluminescence of red (R), green (G), and blue (B) (RGB) colors. A building brick-like assembly method is introduced to realize RGB multicolor emission patterns from this composite material. By sectioning out individual pixels from monochrome-emissive composite sheets, the advantage of the self-healing properties of polyurethane is taken to arrange and weld them into a RGB patterned fabric by brief exposure to ethanol. This provides an approach to form single layer RGB light-emitting pixels, such as potentially required in the display applications, without the use of any lithographic or etching processing. The method can utilize a wide range of different solution-based kinds of light-emitting materials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effectiveness of embodied symbols. The case of a Danish healing ritual

DEFF Research Database (Denmark)

Ostenfeld-Rosenthal, Ann

2010-01-01

images of body and self work to transform the patient during a healing ritual; to develop an understanding of the process of a bodily founded symbolic ‘re-editing’ of body- and self-image, which it is argued is a fundamental art in any healing ritual. Furthermore, I will argue that a charismatic shaman...

Polyampholyte hydrogel electrolytes for flexible and self-healing aqueous supercapacitor for low temperature applications

Science.gov (United States)

Chung, Hyun-Joong; Li, Xinda

Quenched polyampholytes provide a novel class of tough hydrogel that has self-healing ability, strong adhesion, and mechanical flexibility. In this study, we show that the polyampholyte hydrogels can be utilized as an aqueous gel electrolyte material that is especially useful for low temperature operations; at -30 °C, energy density of 10.5 Wh/kg at a power density of 500 W/kg was achieved. The high performance at the low temperature is associated to the concept of non-freezable water near the hydrophilic polymer chains. A comparison between differential scanning calorimetry (DSC) measurements for polyampholytes that contained KOH and neat KOH solution revealed that increased amount of water molecules become non-freezable when the solution is contained in the hydrogel networks. In addition, the crosslinked network structure of the polyampholyte chains disrupts the crystalline growth of ice, resulting in `slush-like' ice formation. The interplay between the increased amount of unfrozen water and the limited growth of ice crystals leads to the enhanced supercapacitor performance at low temperatures.

Generalized hypercube graph $\\Q_n(S$, graph products and self-orthogonal codes

Directory of Open Access Journals (Sweden)

Pani Seneviratne

2016-01-01

Full Text Available A generalized hypercube graph $\\Q_n(S$ has $\\F_{2}^{n}=\\{0,1\\}^n$ as the vertex set and two vertices being adjacent whenever their mutual Hamming distance belongs to $S$, where $n \\ge 1$ and $S\\subseteq \\{1,2,\\ldots, n\\}$. The graph $\\Q_n(\\{1\\}$ is the $n$-cube, usually denoted by $\\Q_n$.We study graph boolean products $G_1 = \\Q_n(S\\times \\Q_1, G_2 = \\Q_{n}(S\\wedge \\Q_1$, $G_3 = \\Q_{n}(S[\\Q_1]$ and show that binary codes from neighborhood designs of $G_1, G_2$ and $G_3$ are self-orthogonal for all choices of $n$ and $S$. More over, we show that the class of codes $C_1$ are self-dual. Further we find subgroups of the automorphism group of these graphs and use these subgroups to obtain PD-sets for permutation decoding. As an example we find a full error-correcting PD set for the binary $[32, 16, 8]$ extremal self-dual code.

A Survey on Smart Agent-Based Microgrids for Resilient/Self-Healing Grids

Directory of Open Access Journals (Sweden)

Kaveh Dehghanpour

2017-05-01

Full Text Available This paper presents an overview of our body of work on the application of smart control techniques for the control and management of microgrids (MGs. The main focus here is on the application of distributed multi-agent system (MAS theory in multi-objective (MO power management of MGs to find the Pareto-front of the MO power management problem. In addition, the paper presents the application of Nash bargaining solution (NBS and the MAS theory to directly obtain the NBS on the Pareto-front. The paper also discusses the progress reported on the above issues from the literature. We also present a MG-based power system architecture for enhancing the resilience and self-healing of the system.

Gaseous core nuclear-driven engines featuring a self-shutoff mechanism to provide nuclear safety

International Nuclear Information System (INIS)

Heidrich, J.; Pettibone, J.; Chow, Tze-Show; Condit, R.; Zimmerman, G.

1991-11-01

Nuclear driven engines are described that could be run in either pulsed or steady state modes. In the pulsed mode nuclear energy is released by fissioning of uranium or plutonium in a supercritical assembly of fuel and working gas. In a steady state mode a fuel-gas mixture is injected into a magnetic nozzle where it is compressed into a critical state and produces energy. Engine performance is modeled using a code that calculates hydrodynamics, fission energy production, and neutron transport self-consistently. Results are given demonstrating a large negative temperature coefficient that produces self-shutoff or control of energy production. Reduced fission product inventory and the self-shutoff provide inherent nuclear safety. It is expected that nuclear engine reactor units could be scaled up from about 100 MW e

Theory of pressure-induced islands and self-healing in three-dimensional toroidal magnetohydrodynamic equilibria

International Nuclear Information System (INIS)

Bhattacharjee, A.; Hayashi, T.; Hegna, C.C.; Nakajima, N.; Sato, T.

1994-11-01

The role of singular currents in three-dimensional toroidal equilibria and their resolution by magnetic island formation is discussed from both analytical and computational points of view. Earlier analytical results are extended to include small vacuum islands which may, in general, have different phases with respect to pressure-induced islands. In currentless stellarators, the formation of islands is shown to depend on the resistive parameter D R as well as the integrated effect of global Pfirsch-Schlueter currents. It is demonstrated that the pressure-induced 'self-healing' effect, recently discovered computationally, is also predicted by analytical theory. (author)

Ruthenium Grubbs’ catalyst nanostructures grown by UV-excimer-laser ablation for self-healing applications

International Nuclear Information System (INIS)

Aïssa, B.; Nechache, R.; Haddad, E.; Jamroz, W.; Merle, P.G.; Rosei, F.

2012-01-01

Highlights: ► Successful preparation of 5-Ethylidene-2-Norbornene (5E2N) monomer reacted with Ruthenium Grubbs’ Catalyst (RGC) composite. ► The kinetics of the 5E2N ring opening metathesis polymerization (ROMP) is effective in a large temperature range (−20 to 45 °C). ► The kinetics of the 5E2N ROMP is occurring at very short time scales ( −4 Vol.%, occurring at very short time reaction. This approach opens new prospects for using healing agent nanocomposite materials for self-repair functionality, thereby obtaining a higher catalytic efficiency per unit mass.

Structural stability and self-healing capability of Er2O3 in situ coating on V-4Cr-4Ti in liquid lithium

International Nuclear Information System (INIS)

Yao, Zhenyu; Suzuki, Akihiro; Muroga, Takeo; Nagasaka, Takuya

2006-01-01

The in situ Er 2 O 3 insulating coating is under development for the self-cooled Li/V-alloy type fusion blanket. In this study, the structural stability and self-healing capability of the coating are investigated. Since the cracking in the coating was not observed after exposure when Li was removed with a weak lotion (liquid NH 3 ), the cracking observed in the previous studies is not a practical issue in a real blanket. The re-exposure of the coating in pure Li showed that the coating once formed in Li (Er) is thought to be stable in pure Li. Thus, coating has the possibility to be serviced in a Li environment without an Er supply. By prior exposure to Li (Er) at 873 K, the exhaustion of the oxygen storage in V-alloy substrate during exposure at 973 K could be delayed effectively. The self-healing capability of the coating was demonstrated by the examination with the re-exposing cracked coating in Li (Er)

Self-Esteem and Academic Difficulties in Preadolescents and Adolescents Healed from Paediatric Leukaemia.

Science.gov (United States)

Tremolada, Marta; Taverna, Livia; Bonichini, Sabrina; Basso, Giuseppe; Pillon, Marta

2017-05-24

Adolescents with cancer may demonstrate problems in their self-esteem and schooling. This study aims to screen the preadolescents and adolescents more at risk in their self-esteem perception and schooling difficulties post-five years from the end of therapy. Twenty-five paediatric ex-patients healed from leukaemia were recruited at the Haematology-Oncologic Clinic (University of Padua). The mean age of the children was 13.64 years (Standard Deviation (SD)) = 3.08, range = 10-19 years), most were treated for acute lymphoblastic leukaemia (ALL) (84%) and relatively equally distributed by gender. They filled in the Multidimensional Self-Esteem Test, while parents completed a questionnaire on their child's schooling. Global self-esteem was mostly below the 50 percentile (58.5%), especially regarding interpersonal relationships (75%). An independent sample t -test showed significant mean differences on the emotionality scale ( t = 2.23; degree of freedom (df) = 24; p = 0.03) and in the bodily experience scale ( t = 3.02; df = 24; p = 0.006) with survivors of Acute Myeloid Leukaemia (AML) having lower scores. An Analysis of Variance (ANOVA ) showed significant mean differences in the bodily experience scale ( F = 12.31; df = 2, p = 0.0001) depending on the survivors' assigned risk band. The parent reports showed that 43.5% of children had difficulties at school. Childhood AML survivors with a high-risk treatment were more at risk in their self-esteem perceptions. Preventive interventions focusing on self-esteem and scholastic wellbeing are suggested in order to help their return to their normal schedules.

Self-healing phenomena on corroding steel in simulated pore water and mortar, substantiated via cyclic voltammetry and surface analysis

Energy Technology Data Exchange (ETDEWEB)

Koleva, D. A.; Breugel, K. van [Delft University of Technology, The Netherlands Faculty of CiTG, Department Materials and Environment, Delf (Netherlands); Hu, J. [School of Materials Science and Engineering, South China University of Technology, Guangzhou (China); Kolev, H. [Bulgarian Academy of Sciences, Institute of Catalysis, Sofia (Bulgaria)

2013-07-01

The application of polymeric nano-particles was investigated as an approach to control corrosion and/or self-heal corrosion damage on steel in simulated alkaline medium and reinforced mortar. The “self-healing agent”, present in the closed inner volume of PEO-b-PS vesicles was Ca-based and chosen as such due to the natural predominance of Ca in the investigated system. The vesicles’ concentration was 0.0024 wt.% in the model medium and 0.025 wt.% per cement weight for the case of mortar. Therefore, a “self-repair” or “self-healing” of the steel product layer solely due to the Ca- component is not realistic in view of these minimal concentrations. The most plausible mechanism is the nature of incorporation of the Ca-containing vesicles in the product layer, enhanced chloride binding effects and adsorption on active sites on the steel surface. A more uniform and stable surface layer, initial pitting formation and propagation, but consecutive “healing”, are evidenced by surface analysis and electrochemical response i.e. largely reduced anodic and corrosion currents and no further pit propagation are observed when Ca-containing vesicles are present in the model medium. Corrosion products-free steel/cement paste interface is relevant for the reinforced mortar, containing Ca-rich vesicles in contrast to vesicles-free and empty vesicles-containing matrix. Key words: corrosion; concrete; polymeric nano-particles; CVA; SEM; XRD; XPS.

Prescription for herbal healing

National Research Council Canada - National Science Library

Balch, Phyllis A; Bell, Stacey J

2012-01-01

.... From the most trusted name in natural healing, Phyllis A. Balch's new edition of Prescription for Herbal Healing provides the most current research and comprehensive facts in an easy-to-read A- to-Z format, including...

Room-temperature healing of a thermosetting polymer using the Diels-Alder reaction.

Science.gov (United States)

Peterson, Amy M; Jensen, Robert E; Palmese, Giuseppe R

2010-04-01

Self-healing materials are particularly desirable for load-bearing applications because they offer the potential for increased safety and material lifetimes. A furan-functionalized polymer network was designed that can heal via covalent bonding across the crack surface with the use of a healing agent consisting of a bismaleimide in solution. Average healing efficiencies of approximately 70% were observed. The healing ability of fiber-reinforced composite specimens was investigated with flexural, short beam shear, and double cantilever beam specimens. It was found that solvent amount and maleimide concentration play key roles in determining healing efficiency.

New improvements in the self-shielding formalism of the Apollo-2 code

International Nuclear Information System (INIS)

Coste, M.; Tellier, H.; Ribon, P.; Raepsaet, V.; Van der Gucht, C.

1993-01-01

One important modelization of a transport code working on a coarse energy mesh is the self-shielding. The French transport code APPOLO 2, developed at the Commissariat a l'Energie Atomique, uses a self-shielding formalism based on a double equivalence. First a homogenization gives the reaction rates in a heterogeneous geometry, and then a multigroup equivalence gives, once the reaction rates are known, the self-shielded cross-sections. The homogenization is a very sensitive part because it is the one which requires physical modelizations. We have added a new model which allows us to treat numerous narrow resonances statistically distributed in the same group of the multigroup mesh. It is important to notice that for a narrow resonance isolated in a group, that new model is equivalent to the previous narrow resonance model (NR)

Anti-Oxidative and Antibacterial Self-Healing Edible Polyelectrolyte Multilayer Film in Fresh-Cut Fruits.

Science.gov (United States)

Liu, Xuefan; Han, Wei; Zhu, Yanxi; Xuan, Hongyun; Ren, Jiaoyu; Zhang, Jianhao; Ge, Liqin

2018-04-01

The consumption of fresh-cut fruits is limited because of the oxidation browning and pathogenic bacteria's growth on the fruit surface. Besides, crack of the fresh-keeping film may shorten the preservation time of fruit. In this work, polyelectrolyte multilayer (PEM) film was fabricated by layer-by-layer (LBL) electrostatic deposition method. The film was made by carboxy methylcellulose sodium (CMC) and chitosan (CS). The as-prepared PEM film had good anti-oxidative and antibacterial capability. It inhibited the growth of Gram-negative bacteria and the antibacterial rate was more than 95%. The stratified structure and linear increase of the absorbance in the film verified a linear increase of film thickness. The slight scratched film could self-heal rapidly after the stimulation of water whatever the layer number was. Moreover, the film could heal cracks whose width was far bigger than the thickness. The application of PEM film on fresh-cut apples showed that PEM film had good browning, weight loss and metabolic activity inhibition ability. These results showed that the PEM film is a good candidate as edible film in fresh-cut fruits applications.

Tribological behavior and self-healing functionality of TiNbCN-Ag coatings in wide temperature range

Energy Technology Data Exchange (ETDEWEB)

Bondarev, A.V., E-mail: abondarev88@gmail.com; Kiryukhantsev-Korneev, Ph.V.; Levashov, E.A.; Shtansky, D.V., E-mail: shtansky@shs.misis.ru

2017-02-28

Highlights: • TiNbCN–Ag coatings for wide temperature range tribological applications. • Alloying with Nb and Ag improve tribological properties and oxidation resistance. • Ag-rich TiNbCN coatings show friction coefficient below 0.45 in range of 25–700 °C. • Ag-doped coatings show active oxidation protection and self-healing functionality. - Abstract: Ag- and Nb-doped TiCN coatings with about 2 at.% of Nb and Ag contents varied between 4.0 and 15.1 at.% were designed as promising materials for tribological applications in a wide temperature range. We report on the structure, mechanical, and tribological properties of TiNbCN-Ag coatings fabricated by simultaneous co-sputtering of TiC{sub 0.5} + 10%Nb{sub 2}C and Ag targets in comparison with those of Ag-free coating. The tribological characteristics were evaluated during constant-temperature tests both at room temperature and 300 °C, as well as during dynamic temperature ramp tests in the range of 25–700 °C. The coating structure and elemental composition were studied by means of X-ray diffraction, scanning and transmission electron microscopy, and glow discharge optical emission spectroscopy. The coating microstructures and elemental compositions inside wear tracks, as well as the wear products, were examined by scanning electron microscopy, energy-dispersive spectroscopy, and Raman spectroscopy. We demonstrate that simultaneous alloying with Nb and Ag permits to overcome the main drawbacks of TiCN coatings such as their relatively high values of friction coefficient at elevated temperatures and low oxidation resistance. It is shown that a relatively high amount of Ag (15 at.%) is required to provide enhanced tribological behavior in a wide temperature range of 25–700 °C. In addition, the prepared Ag-doped coatings demonstrated active oxidation protection and self-healing functionality due to the segregation of Ag metallic particles in damage areas such as cracks, pin-holes, or oxidation sites.

Robust, Self-Healing Superhydrophobic Fabrics Prepared by One-Step Coating of PDMS and Octadecylamine

Science.gov (United States)

Xue, Chao-Hua; Bai, Xue; Jia, Shun-Tian

2016-01-01

A robust, self-healing superhydrophobic poly(ethylene terephthalate) (PET) fabric was fabricated by a convenient solution-dipping method using an easily available material system consisting of polydimethylsiloxane and octadecylamine (ODA). The surface roughness was formed by self-roughening of ODA coating on PET fibers without any lithography steps or adding any nanomaterials. The fabric coating was durable to withstand 120 cycles of laundry and 5000 cycles of abrasion without apparently changing the superhydrophobicity. More interestingly, the fabric can restore its super liquid-repellent property by 72 h at room temperature even after 20000 cycles of abrasion. Meanwhile, after being damaged chemically, the fabric can restore its superhydrophobicity automatically in 12 h at room temperature or by a short-time heating treatment. We envision that this simple but effective coating system may lead to the development of robust protective clothing for various applications. PMID:27264995

Self-organization at the frictional interface for green tribology.

Science.gov (United States)

Nosonovsky, Michael

2010-10-28

Despite the fact that self-organization during friction has received relatively little attention from tribologists so far, it has the potential for the creation of self-healing and self-lubricating materials, which are important for green or environment-friendly tribology. The principles of the thermodynamics of irreversible processes and of the nonlinear theory of dynamical systems are used to investigate the formation of spatial and temporal structures during friction. The transition to the self-organized state with low friction and wear occurs through destabilization of steady-state (stationary) sliding. The criterion for destabilization is formulated and several examples are discussed: the formation of a protective film, microtopography evolution and slip waves. The pattern formation may involve self-organized criticality and reaction-diffusion systems. A special self-healing mechanism may be embedded into the material by coupling the corresponding required forces. The analysis provides the structure-property relationship, which can be applied for the design optimization of composite self-lubricating and self-healing materials for various ecologically friendly applications and green tribology.

Detecting the Activation of a Self-Healing Mechanism in Concrete by Acoustic Emission and Digital Image Correlation

Directory of Open Access Journals (Sweden)

E. Tsangouri

2013-01-01

Full Text Available Autonomous crack healing in concrete is obtained when encapsulated healing agent is embedded into the material. Cracking damage in concrete elements ruptures the capsules and activates the healing process by healing agent release. Previously, the strength and stiffness recovery as well as the sealing efficiency after autonomous crack repair was well established. However, the mechanisms that trigger capsule breakage remain unknown. In parallel, the conditions under which the crack interacts with embedded capsules stay black-box. In this research, an experimental approach implementing an advanced optical and acoustic method sets up scopes to monitor and justify the crack formation and capsule breakage of concrete samples tested under three-point bending. Digital Image Correlation was used to visualize the crack opening. The optical information was the basis for an extensive and analytical study of the damage by Acoustic Emission analysis. The influence of embedding capsules on the concrete fracture process, the location of capsule damage, and the differentiation between emissions due to capsule rupture and crack formation are presented in this research. A profound observation of the capsules performance provides a clear view of the healing activation process.

Self-Healing and Self-Care for Nurses.

Science.gov (United States)

Crane, Patricia J; Ward, Suzanne F

2016-11-01

The potential effects of self-care techniques to increase nurses' effectiveness and influence positive patient care outcomes have often been underestimated. Today, nurses experience increased stress as a result of more work hours and greater patient loads. Research studies demonstrate the value to an organization and to individuals of educating nurses about self-care. Studies also show that how being aware of individual reaction patterns is vital to learning more effective coping mechanisms. In this article, we discuss the aspects of body, mind, emotions, and spirit as they relate to self-care; present self-care change techniques; and offer some practical self-care exercises. Most self-care skills can be learned and implemented in a short period of time. Nurses are encouraged to experiment with the various techniques to determine the most effective ones for them. Copyright © 2016 AORN, Inc. Published by Elsevier Inc. All rights reserved.

New Surface-Treatment Technique of Concrete Structures Using Crack Repair Stick with Healing Ingredients.

Science.gov (United States)

Ahn, Tae-Ho; Kim, Hong-Gi; Ryou, Jae-Suk

2016-08-04

This study focused on the development of a crack repair stick as a new repair method along with self-healing materials that can be used to easily repair the cracks in a concrete structure at the construction site. In developing this new repair technique, the self-healing efficiency of various cementitious materials was considered. Likewise, a crack repair stick was developed to apply to concrete structures with 0.3 mm or lower crack widths. The crack repair stick was made with different materials, such as cement, an expansive material (C 12 A₇), a swelling material, and calcium carbonate, to endow it with a self-healing property. To verify the performance of the crack repair stick for concrete structures, two types of procedures (field experiment and field absorption test) were carried out. As a result of such procedures, it was concluded that the developed crack repair stick could be used on concrete structures to reduce repair expenses and for the improved workability, usability, and serviceability of such structures. On the other hand, to evaluate the self-healing performance of the crack repair stick, various tests were conducted, such as the relative dynamic modulus of elasticity test, the water tightness test, the water permeability test, observation via a microscope, and scanning electron microscope (SEM) analysis. From the results, it is found that water leakage can be prevented and that the durability of a concrete structure can be improved through self-healing. Also, it was verified that the cracks were perfectly closed after 28 days due to application of the crack repair stick. These results indicate the usability of the crack repair stick for concrete structures, and its self-healing efficiency.

Manchester Coding Option for SpaceWire: Providing Choices for System Level Design

Science.gov (United States)

Rakow, Glenn; Kisin, Alex

2014-01-01

This paper proposes an optional coding scheme for SpaceWire in lieu of the current Data Strobe scheme for three reasons. First reason is to provide a straightforward method for electrical isolation of the interface; secondly to provide ability to reduce the mass and bend radius of the SpaceWire cable; and thirdly to provide a means for a common physical layer over which multiple spacecraft onboard data link protocols could operate for a wide range of data rates. The intent is to accomplish these goals without significant change to existing SpaceWire design investments. The ability to optionally use Manchester coding in place of the current Data Strobe coding provides the ability to DC balanced the signal transitions unlike the SpaceWire Data Strobe coding; and therefore the ability to isolate the electrical interface without concern. Additionally, because the Manchester code has the clock and data encoded on the same signal, the number of wires of the existing SpaceWire cable could be optionally reduced by 50. This reduction could be an important consideration for many users of SpaceWire as indicated by the already existing effort underway by the SpaceWire working group to reduce the cable mass and bend radius by elimination of shields. However, reducing the signal count by half would provide even greater gains. It is proposed to restrict the data rate for the optional Manchester coding to a fixed data rate of 10 Megabits per second (Mbps) in order to make the necessary changes simple and still able to run in current radiation tolerant Field Programmable Gate Arrays (FPGAs). Even with this constraint, 10 Mbps will meet many applications where SpaceWire is used. These include command and control applications and many instruments applications with have moderate data rate. For most NASA flight implementations, SpaceWire designs are in rad-tolerant FPGAs, and the desire to preserve the heritage design investment is important for cost and risk considerations. The

A no-go theorem for a two-dimensional self-correcting quantum memory based on stabilizer codes

International Nuclear Information System (INIS)

Bravyi, Sergey; Terhal, Barbara

2009-01-01

We study properties of stabilizer codes that permit a local description on a regular D-dimensional lattice. Specifically, we assume that the stabilizer group of a code (the gauge group for subsystem codes) can be generated by local Pauli operators such that the support of any generator is bounded by a hypercube of size O(1). Our first result concerns the optimal scaling of the distance d with the linear size of the lattice L. We prove an upper bound d=O(L D-1 ) which is tight for D=1, 2. This bound applies to both subspace and subsystem stabilizer codes. Secondly, we analyze the suitability of stabilizer codes for building a self-correcting quantum memory. Any stabilizer code with geometrically local generators can be naturally transformed to a local Hamiltonian penalizing states that violate the stabilizer condition. A degenerate ground state of this Hamiltonian corresponds to the logical subspace of the code. We prove that for D=1, 2, different logical states can be mapped into each other by a sequence of single-qubit Pauli errors such that the energy of all intermediate states is upper bounded by a constant independent of the lattice size L. The same result holds if there are unused logical qubits that are treated as 'gauge qubits'. It demonstrates that a self-correcting quantum memory cannot be built using stabilizer codes in dimensions D=1, 2. This result is in sharp contrast with the existence of a classical self-correcting memory in the form of a two-dimensional (2D) ferromagnet. Our results leave open the possibility for a self-correcting quantum memory based on 2D subsystem codes or on 3D subspace or subsystem codes.

Multiple self-healing squamous epithelioma is caused by a disease-specific spectrum of mutations in TGFBR1

DEFF Research Database (Denmark)

Goudie, David R; D'Alessandro, Mariella; Merriman, Barry

2011-01-01

Multiple self-healing squamous epithelioma (MSSE), also known as Ferguson-Smith disease (FSD), is an autosomal-dominant skin cancer condition characterized by multiple squamous-carcinoma-like locally invasive skin tumors that grow rapidly for a few weeks before spontaneously regressing, leaving s......-of-function TGFBR1 mutations and MSSE. This distinguishes MSSE from the Marfan syndrome-related disorders in which missense mutations in TGFBR1 lead to developmental defects with vascular involvement but no reported predisposition to cancer....

Multiple self-healing squamous epithelioma is caused by a disease-specific spectrum of mutations in TGFBR1

DEFF Research Database (Denmark)

Goudie, David R; D'Alessandro, Mariella; Merriman, Barry

2011-01-01

Multiple self-healing squamous epithelioma (MSSE), also known as Ferguson-Smith disease (FSD), is an autosomal-dominant skin cancer condition characterized by multiple squamous-carcinoma-like locally invasive skin tumors that grow rapidly for a few weeks before spontaneously regressing, leaving......-of-function TGFBR1 mutations and MSSE. This distinguishes MSSE from the Marfan syndrome-related disorders in which missense mutations in TGFBR1 lead to developmental defects with vascular involvement but no reported predisposition to cancer....

Healing: through the lens of intentionality.

Science.gov (United States)

Zahourek, Rothlyn P

2012-01-01

Understanding and studying healing is one of our challenges as health care providers. This study is a presentation of a secondary analysis of data collected to study intentionality in the context of healing. Six healers and 6 healees, five of each who participate as dyads, described their experiences and their concepts of healing. The theory, Intentionality: the Matrix for Healing (IMH), is presented along with a more expanded definition of healing as an awareness of shift and a transformative process.

Self-Shielding Treatment to Perform Cell Calculation for Seed Furl In Th/U Pwr Using Dragon Code

Directory of Open Access Journals (Sweden)

Ahmed Amin El Said Abd El Hameed

2015-08-01

Full Text Available Time and precision of the results are the most important factors in any code used for nuclear calculations. Despite of the high accuracy of Monte Carlo codes, MCNP and Serpent, in many cases their relatively long computational time leads to difficulties in using any of them as the main calculation code. Usually, Monte Carlo codes are used only to benchmark the results. The deterministic codes, which are usually used in nuclear reactor’s calculations, have limited precision, due to the approximations in the methods used to solve the multi-group transport equation. Self- Shielding treatment, an algorithm that produces an average cross-section defined over the complete energy domain of the neutrons in a nuclear reactor, is responsible for the biggest error in any deterministic codes. There are mainly two resonance self-shielding models commonly applied: models based on equivalence and dilution and models based on subgroup approach. The fundamental problem with any self-shielding method is that it treats any isotope as there are no other isotopes with resonance present in the reactor. The most practical way to solve this problem is to use multi-energy groups (50-200 that are chosen in a way that allows us to use all major resonances without self-shielding. In this paper, we perform cell calculations, for a fresh seed fuel pin which is used in thorium/uranium reactors, by solving 172 energy group transport equation using the deterministic DRAGON code, for the two types of self-shielding models (equivalence and dilution models and subgroup models Using WIMS-D5 and DRAGON data libraries. The results are then tested by comparing it with the stochastic MCNP5 code.  We also tested the sensitivity of the results to a specific change in self-shielding method implemented, for example the effect of applying Livolant-Jeanpierre Normalization scheme and Rimman Integration improvement on the equivalence and dilution method, and the effect of using Ribbon

Pathways to Healing: Person-centered Responses to Complementary Services

Science.gov (United States)

Bertrand, Sharon W.; Fermon, Barbara; Coleman, Julie Foley

2014-01-01

Objectives: This research study assessed perceived changes in quality-of-life measures related to participation in complementary services consisting of a variety of nontraditional therapies and/or programs at Pathways: A Health Crisis Resource Center in Minneapolis, Minnesota. Design: Survey data were used to assess perceived changes participants ascribed to their experience with complementary services at Pathways. Quantitative data analysis was conducted using participant demographics together with participant ratings of items from the “Self-Assessment of Change” (SAC) measure developed at the University of Arizona, Tucson. Qualitative data analysis was conducted on written responses to an additional survey question: “To what extent has your participation at Pathways influenced your healing process?” Setting/Location: Pathways offers a variety of services, including one-to-one sessions using nontraditional healing therapies, support groups, educational classes, and practice groups such as yoga and meditation for those facing serious health challenges. These services are offered free of charge through community financial support using volunteer practitioners. Participants: People (126) diagnosed with serious health challenges who used Pathways services from 2007 through 2009. Interventions: Participation in self-selected Pathways services. Measures: Responses to items on the SAC measure plus written responses to the question, “To what extent has your participation at Pathways influenced your healing process?” Results: Quantitative findings: Participants reported experiencing significant changes across all components of the SAC measure. Qualitative findings: Responses to the open-ended survey question identified perspectives on the culture of Pathways and a shift in participants' perceptions of well-being based on their experience of Pathways services. Conclusions: Participation in services provided by the Pathways organization improved perceptions of

Microencapsulation of gallium-indium (Ga-In) liquid metal for self-healing applications.

Science.gov (United States)

Blaiszik, B J; Jones, A R; Sottos, N R; White, S R

2014-01-01

Microcapsules containing a liquid metal alloy core of gallium-indium (Ga-In) are prepared via in situ urea-formaldehyde (UF) microencapsulation. The capsule size, shape, thermal properties, and shell wall thickness are investigated. We prepare ellipsoidal capsules with major and minor diameter aspect ratios ranging from 1.64 to 1.08 and with major diameters ranging from 245 µm to 3 µm. We observe that as the capsule major diameter decreases, the aspect ratio approaches 1. The thermal properties of the prepared microcapsules are investigated by thermogravimetric (TGA) and differential scanning calorimetry (DSC). Microcapsules are shown to survive incorporation into an epoxy matrix and to trigger via mechanical damage to the cured matrix. Microcapsules containing liquid metal cores may have diverse applications ranging from self-healing to contrast enhancement or the demonstration of mechano-adaptive circuitry.

A hybrid optic-fiber sensor network with the function of self-diagnosis and self-healing

Science.gov (United States)

Xu, Shibo; Liu, Tiegen; Ge, Chunfeng; Chen, Cheng; Zhang, Hongxia

2014-11-01

We develop a hybrid wavelength division multiplexing optical fiber network with distributed fiber-optic sensors and quasi-distributed FBG sensor arrays which detect vibrations, temperatures and strains at the same time. The network has the ability to locate the failure sites automatically designated as self-diagnosis and make protective switching to reestablish sensing service designated as self-healing by cooperative work of software and hardware. The processes above are accomplished by master-slave processors with the help of optical and wireless telemetry signals. All the sensing and optical telemetry signals transmit in the same fiber either working fiber or backup fiber. We take wavelength 1450nm as downstream signal and wavelength 1350nm as upstream signal to control the network in normal circumstances, both signals are sent by a light emitting node of the corresponding processor. There is also a continuous laser wavelength 1310nm sent by each node and received by next node on both working and backup fibers to monitor their healthy states, but it does not carry any message like telemetry signals do. When fibers of two sensor units are completely damaged, the master processor will lose the communication with the node between the damaged ones.However we install RF module in each node to solve the possible problem. Finally, the whole network state is transmitted to host computer by master processor. Operator could know and control the network by human-machine interface if needed.

Self-healing of sandwich structures with a grid stiffened shape memory polymer syntactic foam core

Science.gov (United States)

John, Manu; Li, Guoqiang

2010-07-01

In this paper, a new sandwich with an orthogrid stiffened shape memory polymer (SMP) based syntactic foam core was proposed, fabricated, programmed, impacted, healed (sealed), and compression tested, for the purposes of healing impact damage repeatedly and almost autonomously. Two prestrain levels (3% and 20%), two impact energy levels (30.0 and 53.3 J), and two recovery (healing) conditions (2D confined and 3D confined) were employed in this paper. Up to seven impact-healing cycles were conducted. Macroscopic and microscopic damage-healing observation and analysis were implemented. Residual strength was evaluated using an anti-buckling compression test fixture. It was found that the healing efficiency was over 100% for almost all the impact-healing cycles; programming using 20% prestrain led to higher residual strength than that with 3% prestrain; 3D confined recovery resulted in higher residual strength than 2D confined recovery; and as the impact energy increased, the healing efficiency slightly decreased.

Moving to different streams of healing praxis: A reformed missionary approach of healing in the African context

Directory of Open Access Journals (Sweden)

Thinandavha D. Mashau

2016-03-01

Full Text Available There are different streams of healing praxis in Africa today, namely African traditional healing, biomedical healing and spiritual healing (which includes the more recent �touch your TV screen� healing method among others. These streams offer contemporary African people diverse alternatives with regard to healing. As much as the hegemony of Western biomedicine, as endorsed by missionaries in the past, can no longer serve as a norm in the area of healing, we can also not use the African traditional healing methods and or any other alternative presented to Africa without discernment. This suggests therefore that Reformed mission ecclesiology and missionary practitioners should critically engage the African context, worldview and culture on the matter of healing. It should also engage other forms of spiritual healing methods on offer in the African soil.Intradisciplinary and/or interdisciplinary implications: The use of an indigenous knowledge system when coming to healing in the African context, alongside Western biomedicine and other forms of spiritual healing practices, provides African people with diverse alternatives. It also poses a missiological question regarding the acceptability of such a practice within the framework of the Reformed Missionary Paradigm.Keywords: healing; praxis; Reformed; Missionary; Africa

Puncture-Healing Thermoplastic Resin Carbon-Fiber-Reinforced Composites

Science.gov (United States)

Gordon, Keith L. (Inventor); Siochi, Emilie J. (Inventor); Grimsley, Brian W. (Inventor); Cano, Roberto J. (Inventor); Czabaj, Michael W. (Inventor)

2015-01-01

A composite comprising a combination of a self-healing polymer matrix and a carbon fiber reinforcement is described. In one embodiment, the matrix is a polybutadiene graft copolymer matrix, such as polybutadiene graft copolymer comprising poly(butadiene)-graft-poly(methyl acrylate-co-acrylonitrile). A method of fabricating the composite is also described, comprising the steps of manufacturing a pre-impregnated unidirectional carbon fiber preform by wetting a plurality of carbon fibers with a solution, the solution comprising a self-healing polymer and a solvent, and curing the preform. A method of repairing a structure made from the composite of the invention is described. A novel prepreg material used to manufacture the composite of the invention is described.

McCandless's Response to "Soul Healing: A Model of Feminist Therapy."

Science.gov (United States)

McCandless, J. Bardarah

1993-01-01

Responds to Patricia Berliner's "Soul Healing: A Model of Feminist Therapy." Describes Berliner's retreat-workshops for women. Concludes that "Soul Healing" is a thought-provoking article that awakens sensitivities to the problems of poor self-image with which many women struggle and introduces numerous germinal ideas about…

One-Pot Automated Synthesis of Quasi Triblock Copolymers for Self-Healing Physically Crosslinked Hydrogels.

Science.gov (United States)

Voorhaar, Lenny; De Meyer, Bernhard; Du Prez, Filip; Hoogenboom, Richard

2016-10-01

The preparation of physically crosslinked hydrogels from quasi ABA-triblock copolymers with a water-soluble middle block and hydrophobic end groups is reported. The hydrophilic monomer N-acryloylmorpholine is copolymerized with hydrophobic isobornyl acrylate via a one-pot sequential monomer addition through reversible addition fragmentation chain-transfer (RAFT) polymerization in an automated parallel synthesizer, allowing systematic variation of polymer chain length and hydrophobic-hydrophilic ratio. Hydrophobic interactions between the outer blocks cause them to phase-separate into larger hydrophobic domains in water, forming physical crosslinks between the polymers. The resulting hydrogels are studied using rheology and their self-healing ability after large strain damage is shown. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hierarchical system for autonomous sensing-healing of delamination in large-scale composite structures

International Nuclear Information System (INIS)

Minakuchi, Shu; Sun, Denghao; Takeda, Nobuo

2014-01-01

This study combines our hierarchical fiber-optic-based delamination detection system with a microvascular self-healing material to develop the first autonomous sensing-healing system applicable to large-scale composite structures. In this combined system, embedded vascular modules are connected through check valves to a surface-mounted supply tube of a pressurized healing agent while fiber-optic-based sensors monitor the internal pressure of these vascular modules. When delamination occurs, the healing agent flows into the vascular modules breached by the delamination and infiltrates the damage for healing. At the same time, the pressure sensors identify the damaged modules by detecting internal pressure changes. This paper begins by describing the basic concept of the combined system and by discussing the advantages that arise from its hierarchical nature. The feasibility of the system is then confirmed through delamination infiltration tests. Finally, the hierarchical system is validated in a plate specimen by focusing on the detection and infiltration of the damage. Its self-diagnostic function is also demonstrated. (paper)

Exercise accelerates wound healing among healthy older adults: a preliminary investigation.

Science.gov (United States)

Emery, Charles F; Kiecolt-Glaser, Janice K; Glaser, Ronald; Malarkey, William B; Frid, David J

2005-11-01

Older adults are likely to experience delayed rates of wound healing, impaired neuroendocrine responsiveness, and increased daily stress. Exercise activity has been shown to have a positive effect on physiological functioning and psychological functioning among older adults. This study evaluated the effect of a 3-month exercise program on wound healing, neuroendocrine function, and perceived stress among healthy older adults. Twenty-eight healthy older adults (mean age 61.0 +/- 5.5 years) were assigned randomly to an exercise activity group (n = 13) or to a nonexercise control group (n = 15). One month following baseline randomization, after exercise participants had acclimated to the exercise routine, all participants underwent an experimental wound procedure. Wounds were measured 3 times per week until healed to calculate rate of wound healing. All participants completed assessments of exercise endurance, salivary cortisol, and self-reported stress prior to randomization and at the conclusion of the intervention. Exercise participants achieved significant improvements in cardiorespiratory fitness, as reflected by increased oxygen consumption (VO(2)max) and exercise duration. Wound healing occurred at a significantly faster rate in the exercise group [mean = 29.2 (9.0) days] than in the nonexercise group [38.9 (7.4) days; p =.012]. Exercise participants also experienced increased cortisol secretion during stress testing following the intervention. Group differences in wound healing and neuroendocrine responsiveness were found despite low levels of self-reported stress. A relatively short-term exercise intervention is associated with enhanced rates of wound healing among healthy older adults. Thus, exercise activity may be an important component of health care to promote wound healing.

Self-correcting quantum computers

International Nuclear Information System (INIS)

Bombin, H; Chhajlany, R W; Horodecki, M; Martin-Delgado, M A

2013-01-01

Is the notion of a quantum computer (QC) resilient to thermal noise unphysical? We address this question from a constructive perspective and show that local quantum Hamiltonian models provide self-correcting QCs. To this end, we first give a sufficient condition on the connectedness of excitations for a stabilizer code model to be a self-correcting quantum memory. We then study the two main examples of topological stabilizer codes in arbitrary dimensions and establish their self-correcting capabilities. Also, we address the transversality properties of topological color codes, showing that six-dimensional color codes provide a self-correcting model that allows the transversal and local implementation of a universal set of operations in seven spatial dimensions. Finally, we give a procedure for initializing such quantum memories at finite temperature. (paper)

SAGE - MULTIDIMENSIONAL SELF-ADAPTIVE GRID CODE

Science.gov (United States)

Davies, C. B.

1994-01-01

SAGE, Self Adaptive Grid codE, is a flexible tool for adapting and restructuring both 2D and 3D grids. Solution-adaptive grid methods are useful tools for efficient and accurate flow predictions. In supersonic and hypersonic flows, strong gradient regions such as shocks, contact discontinuities, shear layers, etc., require careful distribution of grid points to minimize grid error and produce accurate flow-field predictions. SAGE helps the user obtain more accurate solutions by intelligently redistributing (i.e. adapting) the original grid points based on an initial or interim flow-field solution. The user then computes a new solution using the adapted grid as input to the flow solver. The adaptive-grid methodology poses the problem in an algebraic, unidirectional manner for multi-dimensional adaptations. The procedure is analogous to applying tension and torsion spring forces proportional to the local flow gradient at every grid point and finding the equilibrium position of the resulting system of grid points. The multi-dimensional problem of grid adaption is split into a series of one-dimensional problems along the computational coordinate lines. The reduced one dimensional problem then requires a tridiagonal solver to find the location of grid points along a coordinate line. Multi-directional adaption is achieved by the sequential application of the method in each coordinate direction. The tension forces direct the redistribution of points to the strong gradient region. To maintain smoothness and a measure of orthogonality of grid lines, torsional forces are introduced that relate information between the family of lines adjacent to one another. The smoothness and orthogonality constraints are direction-dependent, since they relate only the coordinate lines that are being adapted to the neighboring lines that have already been adapted. Therefore the solutions are non-unique and depend on the order and direction of adaption. Non-uniqueness of the adapted grid is

Self-Healing and Thermo-Responsive Dual-Crosslinked Alginate Hydrogels based on Supramolecular Inclusion Complexes

Science.gov (United States)

Miao, Tianxin; Fenn, Spencer L.; Charron, Patrick N.; Oldinski, Rachael A.

2015-01-01

β-cyclodextrin (β-CD), with a lipophilic inner cavity and hydrophilic outer surface, interacts with a large variety of non-polar guest molecules to form non-covalent inclusion complexes. Conjugation of β-CD onto biomacromolecules can form physically-crosslinked hydrogel networks upon mixing with a guest molecule. Herein describes the development and characterization of self-healing, thermo-responsive hydrogels, based on host-guest inclusion complexes between alginate-graft-β-CD and Pluronic® F108 (poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol)). The mechanics, flow characteristics, and thermal response were contingent on the polymer concentrations, and the host-guest molar ratio. Transient and reversible physical crosslinking between host and guest polymers governed self-assembly, allowing flow under shear stress, and facilitating complete recovery of the material properties within a few seconds of unloading. The mechanical properties of the dual-crosslinked, multi-stimuli responsive hydrogels were tuned as high as 30 kPa at body temperature, and are advantageous for biomedical applications such as drug delivery and cell transplantation. PMID:26509214

In Operando Self-Healing of Perovskite Electrocatalysts: A Case Study of SrCoO3 for the Oxygen Evolution Reaction

KAUST Repository

Tahini, Hassan A.; Tan, Xin; Schwingenschlö gl, Udo; Smith, Sean C.

2017-01-01

Perovskites are promising catalysts for oxygen evolution reactions (OER); among them, SrCoO3 is one of the best for these reactions. We study the O* intermediates and the role of surface oxygen vacancies of SrCoO3 during OER. A self-healing mechanism is proposed in which O* are incorporated into the surface to recover the redox capabilities of the material.

In Operando Self-Healing of Perovskite Electrocatalysts: A Case Study of SrCoO3 for the Oxygen Evolution Reaction

KAUST Repository

Tahini, Hassan A.

2017-01-24

Perovskites are promising catalysts for oxygen evolution reactions (OER); among them, SrCoO3 is one of the best for these reactions. We study the O* intermediates and the role of surface oxygen vacancies of SrCoO3 during OER. A self-healing mechanism is proposed in which O* are incorporated into the surface to recover the redox capabilities of the material.

Healing history? Aboriginal healing, historical trauma, and personal responsibility.

Science.gov (United States)

Waldram, James B

2014-06-01

What can an exploration of contemporary Aboriginal healing programs such as those offered in Canadian prisons and urban clinics tell us about the importance of history in understanding social and psychological pathology, and more significantly the salience of the concept of "historical trauma"? The form of Aboriginal "healing" that has emerged in recent decades to become dominant in many parts of the country is itself a reflection of historical processes and efforts to ameliorate the consequences of what is today often termed "historical trauma." In other words, contemporary notions of "healing" and the social, cultural, medical, and psychological disruption and distress caused by colonialism and captured in the term "historical trauma" have coevolved in an interdependent manner. I also argue that there is a tension between the attribution of this distress to both specific (e.g., residential schools) and generalized (e.g., colonialism) historical factors, as evident in the "historical trauma" concept, and the prevailing emphasis in many healing programs to encourage the individual to take personal responsibility for their situation and avoid attributing blame to other factors. I conclude that "historical trauma" represents an idiom of distress that captures a variety of historical and contemporary phenomena and which provides a language for expressing distress that is gaining currency, at least among scholars, and that the contemporary Aboriginal healing movement represents an effort to deal with the absence or failure of both "traditional" Aboriginal healing and government-sponsored medical and psychological services to adequately deal with this distress of colonialism. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Drug tourism or spiritual healing? Ayahuasca seekers in Amazonia.

Science.gov (United States)

Winkelman, Michael

2005-06-01

This research addresses the question of whether Westerners who seek traditional spiritual medicine known as ayahuasca can be best characterized as "drug tourists" or as people pursuing spiritual and therapeutic opportunities. Participants in an ayahuasca retreat in Amazonia were interviewed regarding their motivations for participation and the benefits they felt that they received. These findings from the interviews were organized to reveal common motivations and benefits. Contrary to the characterization as "drug tourists", the principal motivations can be characterized as: seeking spiritual relations and personal spiritual development; emotional healing; and the development of personal self-awareness, including contact with a sacred nature, God, spirits and plant and natural energies produced by the ayahuasca. The motivation and perceived benefits both point to transpersonal concerns, with the principal perceived benefits involving increased self awareness, insights and access to deeper levels of the self that enhanced personal development and the higher self, providing personal direction in life.

Symbolic healing of early psychosis: psychoeducation and sociocultural processes of recovery.

Science.gov (United States)

Larsen, John Aggergaard

2007-09-01

This article analyzes sociocultural processes of recovery in a Danish mental health service providing two years of integrated biopsychosocial treatment following first-episode psychosis. The study is based on ethnographic research in the service and person-centered involvement with 15 clients. The analysis applies Dow's [1986 American Anthropologist 88:56-69] model of universal components of symbolic healing to elucidate sociocultural aspects of therapeutic efficacy that are alternatively disregarded as placebo or nonspecific effects. It is demonstrated how staff engaged with clients to deliver "psychoeducation" that provided scientific and biomedical theories about mental illness, constituting a shared "mythic world" that was accepted as an experiential truth and used to explain clients' illness experiences. The analysis highlights the need to supplement attention in Dow's model to the healing procedure with consideration of variability in the healing process. Depending on individual responses to the intervention, the staff's professional backgrounds and staff-client relationships different recovery models were applied. One suggested "episodic psychosis" and full recovery, and the other suggested "chronic schizophrenia" and the necessity of comprehensive life adjustments to the mental illness. The recovery models influenced clients' perspectives on illness and self as they engaged in identity work, negotiating future plans and individual life projects by including also alternative systems of explanation from the wider cultural repertoire.

An immune-inspired swarm aggregation algorithm for self-healing swarm robotic systems.

Science.gov (United States)

Timmis, J; Ismail, A R; Bjerknes, J D; Winfield, A F T

2016-08-01

Swarm robotics is concerned with the decentralised coordination of multiple robots having only limited communication and interaction abilities. Although fault tolerance and robustness to individual robot failures have often been used to justify the use of swarm robotic systems, recent studies have shown that swarm robotic systems are susceptible to certain types of failure. In this paper we propose an approach to self-healing swarm robotic systems and take inspiration from the process of granuloma formation, a process of containment and repair found in the immune system. We use a case study of a swarm performing team work where previous works have demonstrated that partially failed robots have the most detrimental effect on overall swarm behaviour. We have developed an immune inspired approach that permits the recovery from certain failure modes during operation of the swarm, overcoming issues that effect swarm behaviour associated with partially failed robots. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

An assessment of meaning in life-threatening illness: development of the Healing Experience in All Life Stressors (HEALS

Directory of Open Access Journals (Sweden)

Sloan DH

2017-02-01

Full Text Available Danetta Hendricks Sloan,1 Karlynn BrintzenhofeSzoc,2 Tiffany Kichline,1 Karen Baker,1 Jean-Paul Pinzon,1 Christina Tafe,1 Lingsheng Li,1 M Jennifer Cheng,1 Ann Berger1 1Pain and Palliative Care, National Institutes of Health, Clinical Center, Bethesda, MD, 2School of Social Work, College of Allied Health Sciences, University of Cincinnati, Cincinnati, OH, USA Context: Patients with life-threatening or chronic illness report an experience of increased positive psychological, social, and/or spiritual change during diagnosis and/or treatment of their illness, even in the face of unfavorable prognosis. This transformation begins through the ability to make their life meaningful by forming meaningful connections that emerge through self-introspection and relationships with a divine entity, nature, and other people. The Healing Experience in All Life Stressors (HEALS assessment provides a way to identify distress-causing changes that may interfere with the development of meaning and psycho–social–spiritual homeostasis.Objective: Preliminary examination of responses to items on the HEALS and examination of the factor structure.Method: The 48-item HEALS questionnaire was developed using a multistep process: literature review for concept development, item generation from qualitative data, and face and content validity by expert panel. In the current study, HEALS was completed by 100 patients diagnosed with life-limiting disease and seen by the palliative care team at a large research institution in the US. Exploratory factor analysis techniques were used to determine scale structure of the instrument.Results: Outcome testing of sample adequacy using Kaiser–Meyer–Olkin statistic was 0.75, which exceeds the recommended value of 0.60. The HEALS show very good internal consistency with a Cronbach’s a of 0.94. Overall results of the exploratory factor analysis established a four-factor questionnaire: 1 religion; 2 spirituality, demonstrated by a

A self-organized internal models architecture for coding sensory-motor schemes

Directory of Open Access Journals (Sweden)

Esaú eEscobar Juárez

2016-04-01

Full Text Available Cognitive robotics research draws inspiration from theories and models on cognition, as conceived by neuroscience or cognitive psychology, to investigate biologically plausible computational models in artificial agents. In this field, the theoretical framework of Grounded Cognition provides epistemological and methodological grounds for the computational modeling of cognition. It has been stressed in the literature that textit{simulation}, textit{prediction}, and textit{multi-modal integration} are key aspects of cognition and that computational architectures capable of putting them into play in a biologically plausible way are a necessity.Research in this direction has brought extensive empirical evidencesuggesting that textit{Internal Models} are suitable mechanisms forsensory-motor integration. However, current Internal Models architectures show several drawbacks, mainly due to the lack of a unified substrate allowing for a true sensory-motor integration space, enabling flexible and scalable ways to model cognition under the embodiment hypothesis constraints.We propose the Self-Organized Internal ModelsArchitecture (SOIMA, a computational cognitive architecture coded by means of a network of self-organized maps, implementing coupled internal models that allow modeling multi-modal sensory-motor schemes. Our approach addresses integrally the issues of current implementations of Internal Models.We discuss the design and features of the architecture, and provide empirical results on a humanoid robot that demonstrate the benefits and potentialities of the SOIMA concept for studying cognition in artificial agents.

Healing by Gentle Touch Ameliorates Stress and Other Symptoms in People Suffering with Mental Health Disorders or Psychological Stress

Directory of Open Access Journals (Sweden)

Clare Weze

2007-01-01

Full Text Available Previous studies on healing by gentle touch in clients with various illnesses indicated substantial improvements in psychological well-being, suggesting that this form of treatment might be helpful for people with impaired quality of mental health. The purpose of this study was to evaluate the effectiveness and safety of healing by gentle touch in subjects with self-reported impairments in their psychological well-being or mental health. One hundred and forty-seven clients who identified themselves as having psychological problems received four treatment sessions. Pre- to post-treatment changes in psychological and physical functioning were assessed by self-completed questionnaires which included visual analogue scales (VAS and the EuroQoL (EQ-5D. Participants recorded reductions in stress, anxiety and depression scores and increases in relaxation and ability to cope scores (all P < 0.0004. Improvements were greatest in those with the most severe symptoms initially. This open study provides strong circumstantial evidence that healing by gentle touch is safe and effective in improving psychological well-being in participants with self-reported psychological problems, and also that it safely complements standard medical treatment. Controlled trials are warranted.

Faith healing and faith in healing.

Science.gov (United States)

Gopichandran, Vijayaprasad

2015-01-01

Sarkar and Seshadri have presented an interesting paper in this issue on the ethical approach that a physician should take when faced with requests for faith healing (1). The paper describes four approaches that the physician can take. These are rejecting the request, keeping oneself detached from the issue, endorsing the request and trying to understand the practices concerned so as to make a reasoned decision. This commentary attempts to explore the issue of faith healing further, from the point of view of clinical care. It shall discuss five important dimensions which can supplement the arguments by Sarkar and Seshadri. These are the concepts of faith, spirituality and religion and faith healing; the difference between cure and healing; patient-centred care; the various factors influencing a doctor's response to requests for faith healing; and finally, the ethical issues to be considered while making a decision. Before launching into the discussion, it should be made clear that this commentary refers mainly to those faith healing practices which are not overtly harmful, such as prayers, and wearing rings and amulets.

[The Process of Healing Child Physical Abuse: Sprouting and Twining].

Science.gov (United States)

Chang, Hsin-Yi; Feng, Jui-Ying; Tseng, Ren-Mei

2018-06-01

Child physical abuse impacts the physical and psychological health of survivors. Healing child abuse is an essential process that helps survivors reorganize the meaning of the trauma and pursue a normal life. Considering the trauma of child physical abuse within the social context allows the experiences of individual survivors to be reflected in their process of healing. To explore the social interaction and construction process of healing experienced by survivors of child physical abuse. A qualitative research design using grounded theory was applied. Purposive and theoretical sampling was used to recruit survivors of childhood physical abuse who had experienced healing. Semi-structured, in-depth interviews were used and data were analyzed using open, axial, and selective coding. The process of healing child physical abuse in this study was a process of sprouting and twining. Three core categories emerged: thriving, relationships, and ethics. The healing process was analogous to a seed growing in poor soil, sprouting out from the ground, and striving to live by seeking support. The survivors constantly established interactive relationships with their selves and with others and struggled to keep family bonds grounded and growing within the frame of ethics. The healing process of sprouting and twining for child physical abuse survivors in Taiwan integrates thriving, relationships, and ethics. Professionals working with child-physical-abuse survivors must recognize conflicts in ethics. Strategies should be developed to assist survivors to cope with the impact of childhood trauma in order to facilitate the healing process.

Quantum Codes From Negacyclic Codes over Group Ring ( Fq + υFq) G

International Nuclear Information System (INIS)

Koroglu, Mehmet E.; Siap, Irfan

2016-01-01

In this paper, we determine self dual and self orthogonal codes arising from negacyclic codes over the group ring ( F q + υF q ) G . By taking a suitable Gray image of these codes we obtain many good parameter quantum error-correcting codes over F q . (paper)

URR [Unresolved Resonance Region] computer code: A code to calculate resonance neutron cross-section probability tables, Bondarenko self-shielding factors, and self-indication ratios for fissile and fertile nuclides

International Nuclear Information System (INIS)

Leal, L.C.; de Saussure, G.; Perez, R.B.

1990-01-01

The URR computer code has been developed to calculate cross-section probability tables, Bondarenko self-shielding factors, and self-indication ratios for fertile and fissile isotopes in the unresolved resonance region. Monte Carlo methods are utilized to select appropriate resonance parameters and to compute the cross sections at the desired reference energy. The neutron cross sections are calculated by the single-level Breit-Wigner formalism with s-, p-, and d-wave contributions. The cross-section probability tables are constructed by sampling by Doppler broadened cross-sections. The various self-shielding factors are computer numerically as Lebesgue integrals over the cross-section probability tables

Mussel-Inspired Self-Healing Double-Cross-Linked Hydrogels by Controlled Combination of Metal Coordination and Covalent Cross-Linking

DEFF Research Database (Denmark)

Andersen, Amanda; Krogsgaard, Marie; Birkedal, Henrik

2018-01-01

a catechol-based hydrogel design that allows for the degree of oxidative covalent cross-linking to be controlled. Double cross-linked hydrogels with tunable stiffness are constructed by adding the oxidizable catechol analogue, tannic acid, to an oxidation-resistant hydrogel construct held together...... by coordination of the dihydroxy functionality of 1-(2'-carboxyethyl)-2-methyl-3-hydroxy-4-pyridinone to trivalent metal ions. By varying the amount of tannic acid, the hydrogel stiffness can be customized to a given application while retaining the self-healing capabilities of the hydrogel's coordination chemical...

Exploring the Concept of Healing Spaces.

Science.gov (United States)

DuBose, Jennifer; MacAllister, Lorissa; Hadi, Khatereh; Sakallaris, Bonnie

2018-01-01

Evidence-based design (EBD) research has demonstrated the power of environmental design to support improved patient, family, and staff outcomes and to minimize or avoid harm in healthcare settings. While healthcare has primarily focused on fixing the body, there is a growing recognition that our healthcare system could do more by promoting overall wellness, and this requires expanding the focus to healing. This article explores how we can extend what we know from EBD about health impacts of spatial design to the more elusive goal of healing. By breaking the concept of healing into antecedent components (emotional, psychological, social, behavioral, and functional), this review of the literature presents the existing evidence to identify how healthcare spaces can foster healing. The environmental variables found to directly affect or facilitate one or more dimension of healing were organized into six groups of variables-homelike environment, access to views and nature, light, noise control, barrier-free environment, and room layout. While there is limited scientific research confirming design solutions for creating healing spaces, the literature search revealed relationships that provide a basis for a draft definition. Healing spaces evoke a sense of cohesion of the mind, body, and spirit. They support healing intention and foster healing relationships.

Unveiling Cebuano Traditional Healing Practices

Directory of Open Access Journals (Sweden)

ZachiaRaiza Joy S. Berdon

2016-02-01

Full Text Available This study aims to identify the features of Cebuano’s traditional healing practices. Specifically, it also answers the following objectives: analyze traditional healing in Cebuano’s perspectives, explain the traditional healing process practiced in terms of the traditional healers’ belief, and extrapolate perceptions of medical practitioners toward traditional healing. This study made use of qualitative approach, among five traditional healers who performed healing for not less than ten years, in the mountain barangays of Cebu City. These healers served as the primary informants who were selected because of their popularity in healing. The use of open-ended interview in local dialect and naturalistic observation provided a free listing of their verbatim accounts were noted and as primary narratives. Participation in the study was voluntary and participants were interviewed privately after obtaining their consent. The Cebuano traditional healing practices or “panambal” comprise the use of “himolso” (pulse-checking, “palakaw” (petition, “pasubay” (determining what causes the sickness and its possible means of healing, “pangalap” (searching of medicinal plants for “palina” (fumigation, “tayhop” (gentle-blowing, “tutho” (saliva-blowing,“tuob” (boiling, “orasyon” (mystical prayers, “hilot” (massage, and “barang” (sorcery. Though traditional with medical science disapproval, it contributes to a mystical identity of Cebuano healers, as a manifestation of folk Catholicism belief, in order to do a good legacy to the community that needs help. For further study, researchers may conduct further the studies on the: curative effects of medicinal plants in Cebu, psychological effect pulsechecking healed persons by the mananambal, and unmasking the other features of traditional healing.

Thermal neutron self-shielding correction factors for large sample instrumental neutron activation analysis using the MCNP code

International Nuclear Information System (INIS)

Tzika, F.; Stamatelatos, I.E.

2004-01-01

Thermal neutron self-shielding within large samples was studied using the Monte Carlo neutron transport code MCNP. The code enabled a three-dimensional modeling of the actual source and geometry configuration including reactor core, graphite pile and sample. Neutron flux self-shielding correction factors derived for a set of materials of interest for large sample neutron activation analysis are presented and evaluated. Simulations were experimentally verified by measurements performed using activation foils. The results of this study can be applied in order to determine neutron self-shielding factors of unknown samples from the thermal neutron fluxes measured at the surface of the sample

Effect of Polypropylene Fibers on Self-Healing and Dynamic Modulus of Elasticity Recovery of Fiber Reinforced Concrete

Directory of Open Access Journals (Sweden)

Adham El-Newihy

2018-02-01

Full Text Available This study aims to evaluate self-healing properties and recovered dynamic moduli of engineered polypropylene fiber reinforced concrete using non-destructive resonant frequency testing. Two types of polypropylene fibers (0.3% micro and 0.6% macro and two curing conditions have been investigated: Water curing (at ~25 Celsius and air curing. The Impact Resonance Method (IRM has been conducted in both transverse and longitudinal modes on concrete cylinders prior/post crack induction and post healing of cracks. Specimens were pre-cracked at 14 days, obtaining values of crack width in the range of 0.10–0.50 mm. Addition of polypropylene fibers improved the dynamic response of concrete post-cracking by maintaining a fraction of the original resonant frequency and elastic properties. Macro fibers showed better improvement in crack bridging while micro fiber showed a significant recovery of the elastic properties. The results also indicated that air-cured Polypropylene Fiber Reinforced Concrete (PFRC cylinders produced ~300 Hz lower resonant frequencies when compared to water-cured cylinders. The analyses showed that those specimens with micro fibers exhibited a higher recovery of dynamic elastic moduli.

Effect of interpolation error in pre-processing codes on calculations of self-shielding factors and their temperature derivatives

International Nuclear Information System (INIS)

Ganesan, S.; Gopalakrishnan, V.; Ramanadhan, M.M.; Cullan, D.E.

1986-01-01

We investigate the effect of interpolation error in the pre-processing codes LINEAR, RECENT and SIGMA1 on calculations of self-shielding factors and their temperature derivatives. We consider the 2.0347 to 3.3546 keV energy region for 238 U capture, which is the NEACRP benchmark exercise on unresolved parameters. The calculated values of temperature derivatives of self-shielding factors are significantly affected by interpolation error. The sources of problems in both evaluated data and codes are identified and eliminated in the 1985 version of these codes. This paper helps to (1) inform code users to use only 1985 versions of LINEAR, RECENT, and SIGMA1 and (2) inform designers of other code systems where they may have problems and what to do to eliminate their problems. (author)

Effect of interpolation error in pre-processing codes on calculations of self-shielding factors and their temperature derivatives

International Nuclear Information System (INIS)

Ganesan, S.; Gopalakrishnan, V.; Ramanadhan, M.M.; Cullen, D.E.

1985-01-01

The authors investigate the effect of interpolation error in the pre-processing codes LINEAR, RECENT and SIGMA1 on calculations of self-shielding factors and their temperature derivatives. They consider the 2.0347 to 3.3546 keV energy region for /sup 238/U capture, which is the NEACRP benchmark exercise on unresolved parameters. The calculated values of temperature derivatives of self-shielding factors are significantly affected by interpolation error. The sources of problems in both evaluated data and codes are identified and eliminated in the 1985 version of these codes. This paper helps to (1) inform code users to use only 1985 versions of LINEAR, RECENT, and SIGMA1 and (2) inform designers of other code systems where they may have problems and what to do to eliminate their problems

Self-organized computation with unreliable, memristive nanodevices

International Nuclear Information System (INIS)

Snider, G S

2007-01-01

Nanodevices have terrible properties for building Boolean logic systems: high defect rates, high variability, high death rates, drift, and (for the most part) only two terminals. Economical assembly requires that they be dynamical. We argue that strategies aimed at mitigating these limitations, such as defect avoidance/reconfiguration, or applying coding theory to circuit design, present severe scalability and reliability challenges. We instead propose to mitigate device shortcomings and exploit their dynamical character by building self-organizing, self-healing networks that implement massively parallel computations. The key idea is to exploit memristive nanodevice behavior to cheaply implement adaptive, recurrent networks, useful for complex pattern recognition problems. Pulse-based communication allows the designer to make trade-offs between power consumption and processing speed. Self-organization sidesteps the scalability issues of characterization, compilation and configuration. Network dynamics supplies a graceful response to device death. We present simulation results of such a network-a self-organized spatial filter array-that demonstrate its performance as a function of defects and device variation

A code for the calculation of self-absorption fractions of photons

International Nuclear Information System (INIS)

Jaegers, P.; Landsberger, S.

1988-01-01

Neutron activation analysis (NAA) is now a well-established technique used by many researchers and commercial companies. It is often wrongly assumed that these NAA methods are matrix independent over a wide variety of samples. Accuracy at the level of a few percent is often difficult to achieve, since components such as timing, pulse pile-up, high dead-time corrections, sample positioning, and chemical separations may severely compromise the results. One area that has received little attention is the calculation of the effect of self-absorption of gamma-rays (including low-energy ones) in samples, particularly those with major components of high-Z values. The analysis of trace components in lead samples is an obvious example, but other high-Z matrices such as various permutations and combinations of zinc, tin, lead, copper, silver, antimony, etc.; ore concentrates; and meteorites are also affected. The authors have developed a simple but effective personal-computer-compatible user-friendly code, however, which can calculate the amount of energy signal that is lost due to the presence of any amount of one or more Z components. The program is based on Dixon's paper of 1951 for the calculation of self-absorption corrections for linear, cylindrical, and spherical sources. To determine the self-absorption fraction of a photon in a source, the FORTRAN computer code SELFABS was written

Reflection on the Role of the Spirit in Finding Meaning and Healing as Clinicians.

Science.gov (United States)

Jacobs, Carolyn

2018-01-01

Reflections on the Role of the Spirit in Finding Meaning and Healing as Clinicians is based on a presentation for the George Washington Spirituality and Health Summer Institute on July 13, 2017. The presentation invited health care professionals to explore contemplative practices as ways to invite the Spirit to strengthening their resilience in caring for themselves and others. As clinicians, there is often a longing to be grounded in a regular contemplative practice centering one's inner life and to acknowledge the creative energy of the Spirit in relationships. This reflection draws on resilience research that finds that contemplative practices such as deep breathing, meditation, reflective writing, and peer or community support enhance ways of meaning making and healing. Contemplative practices are provided, which can connect clinicians to the Spirit with the purpose of leading to increased meaning and healing in self and relationships. Copyright © 2017 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

The Healing Land : Research Methods in Kalahari Communities ...

African Journals Online (AJOL)

The Healing Land (Isaacson, 2001a) is a vivid, experiential account of Rupert Isaacson's journey towards personal and community healing among the Khomani Bushmen of the Kalahari Desert in South Africa. This paper provides a detailed analysis of The Healing Land in relation to Isaacson's research methodology and ...

ASA24 enables multiple automatically coded self-administered 24-hour recalls and food records

Science.gov (United States)

A freely available web-based tool for epidemiologic, interventional, behavioral, or clinical research from NCI that enables multiple automatically coded self-administered 24-hour recalls and food records.

Exploring Inpatients' Experiences of Healing and Healing Spaces

Directory of Open Access Journals (Sweden)

Lorissa MacAllister PhD, AIA

2016-12-01

Full Text Available In order to understand a patient’s healing experience it is essential to understand the elements that they, the patient, believes contributed to their healing. Previous research has focused on symptom reducers or contributors through environment such as stress. A person’s experience of healing happens over time not instantaneous. Therefore, in this study, the interviews with patients happened after forty-eight hours of hospitalization. This mixed methods study describes the experiences of seventeen inpatients from two healthcare systems using a phenomenological approach combined with evidence based design evaluation methods to document the setting. The qualitative data was analyzed first for reoccurring themes then further explored and defined through quantitative environmental observations. The seventeen patients defined healing as “getting better/well.” Seventy three statements were recorded about contributors and detractors to healing in the physical environment. Three primary themes emerged from the data as positive influencers of a healing experience: being cared for, being comfortable and experiencing something familiar or like home. These results demonstrate that patients perceive their inpatient healing experience through a supported environment.

Analysis of mixed oxides critical experiments using the Hammer-Technion code with self-shielding treatment by Bondarenko method

International Nuclear Information System (INIS)

Abe, Alfredo Y.; Santos, Adimir dos

1995-01-01

The present work summarizes the verification of the treatment of self-shielding based on Bondarenko method in HAMMER-TECHNION cell code for the Pu O 2 -U O 2 critical system using JENDL-3 nuclear data library. The results obtained are in excellent agreement with the original treatment of self-shielding employed by HAMMER-TECHNION cell code. (author). 9 refs, 1 fig, 9 tabs

Evaluation of long-term corrosion durability and self-healing ability of scratched coating systems on carbon steel in a marine environment

Science.gov (United States)

Zhao, Xia; Chen, Changwei; Xu, Weichen; Zhu, Qingjun; Ge, Chengyue; Hou, Baorong

2017-09-01

Defects in protective-coating systems on steel surfaces are inevitable in practical engineering applications. A composite coating system, including a primer, middle coat and topcoat, were used to protect carbon steel from corrosion in a marine environment. Two environmental additives, glass fibers and thiourea, were applied in the middle coat to modify the coating system. The long-term corrosion durability and self-healing ability of the scratched coating system were evaluated by multiple methods. Results of the electrochemical technologies indicated that the coating system that contained 0.5 wt.% fibers and 0.5 wt.% thiourea presented good corrosion protection and self-healing for carbon steel when immersed in 3.5% NaCl for 120 d. Evolution of localized corrosion factors with time, as obtained from the current distribution showed that fibers combined with thiourea could inhibit the occurrence of local corrosion in scratched coating systems and retarded the corrosion development significantly. Surface characterization suggested that adequate thiourea could be absorbed uniformly on fibers for a long time to play an important role in protecting the carbon steel. Finally, schematic models were established to demonstrate the action of fibers and thiourea on the exposed surface of the carbon steel and the scratched coating system in the entire deterioration process.

Healing the body, healing the self: the interrelationship of sickness, health, and faith in the lives of St. Lawrence Island Yupik residents.

Science.gov (United States)

Jolles, Carol Zane

2003-01-01

For about 15 years, Carol Jolles has been traveling to St. Lawrence Island, Alaska to study the role faith plays in the lives of Sivuqaq (Gambell) residents. From the outset, she was aware of the strong presence of two Christian faith traditions in the community. She was present when people “spoke in tongues” (entered a spiritual state, sometimes identified as an altered state of consciousness), and she was aware that people relied on prayer, often uttered in a spiritually inspired context, to ease the pain of daily life and to find the strength to do difficult tasks. Many months passed, however, before she realized that many people relied on faith to heal. From the perspective of her long-term working relationships and friendships with community members, Jolles takes a fresh look at some of the situations from her early work where faith and healing were intertwined. She also looks at more recent examples to place faith-based healing in a more general context. In the process, she focuses on a few special individuals to highlight the components of faith and healing associated with illness and mental distress.

Robust synthesis of epoxy resin-filled microcapsules for application to self-healing materials.

Science.gov (United States)

Bolimowski, Patryk A; Bond, Ian P; Wass, Duncan F

2016-02-28

Mechanically and thermally robust microcapsules containing diglycidyl ether bisphenol A-based epoxy resin and a high-boiling-point organic solvent were synthesized in high yield using in situ polymerization of urea and formaldehyde in an oil-in-water emulsion. Microcapsules were characterized in terms of their size and size distribution, shell surface morphology and thermal resistance to the curing cycles of commercially used epoxy polymers. The size distribution of the capsules and characteristics such as shell thickness can be controlled by the specific parameters of microencapsulation, including concentrations of reagents, stirrer speed and sonication. Selected microcapsules, and separated core and shell materials, were analysed using thermogravimetric analysis and differential scanning calorimetry. It is demonstrated that capsules lose minimal 2.5 wt% at temperatures no higher than 120°C. These microcapsules can be applied to self-healing carbon fibre composite structural materials, with preliminary results showing promising performance. © 2016 The Author(s).

Implementing Internet-Based Self-Care Programs in Primary Care: Qualitative Analysis of Determinants of Practice for Patients and Providers.

Science.gov (United States)

Hermes, Eric; Burrone, Laura; Perez, Elliottnell; Martino, Steve; Rowe, Michael

2018-05-18

Access to evidence-based interventions for common mental health conditions is limited due to geographic distance, scheduling, stigma, and provider availability. Internet-based self-care programs may mitigate these barriers. However, little is known about internet-based self-care program implementation in US health care systems. The objective of this study was to identify determinants of practice for internet-based self-care program use in primary care by eliciting provider and administrator perspectives on internet-based self-care program implementation. The objective was explored through qualitative analysis of semistructured interviews with primary care providers and administrators from the Veterans Health Administration. Participants were identified using a reputation-based snowball design. Interviews focused on identifying determinants of practice for the use of internet-based self-care programs at the point of care in Veterans Health Administration primary care. Qualitative analysis of transcripts was performed using thematic coding. A total of 20 physicians, psychologists, social workers, and nurses participated in interviews. Among this group, internet-based self-care program use was relatively low, but support for the platform was assessed as relatively high. Themes were organized into determinants active at patient and provider levels. Perceived patient-level determinants included literacy, age, internet access, patient expectations, internet-based self-care program fit with patient experiences, interest and motivation, and face-to-face human contact. Perceived provider-level determinants included familiarity with internet-based self-care programs, changes to traditional care delivery, face-to-face human contact, competing demands, and age. This exploration of perspectives on internet-based self-care program implementation among Veterans Health Administration providers and administrators revealed key determinants of practice, which can be used to develop

Definitions of healing and healing interventions across different cultures.

Science.gov (United States)

Lichtenstein, Ann H; Berger, Ann; Cheng, M Jennifer

2017-07-01

For centuries healing has been embedded in non-Western cultures. Traditional cultures believe that healing is derived from the divine and utilize a holistic approach to healing including the body, mind, and spirit. The community and environment are key elements in individual healing along with herbal remedies and ceremonies. Western cultures have accepted some traditional methods of relaxation and exercise, such as yoga and tai chi. In this paper we will examine some similar themes of traditional practices to better understand traditional patients' healing paradigm and find new tools as practitioners of Western medicine.

Self-assembled software and method of overriding software execution

Science.gov (United States)

Bouchard, Ann M.; Osbourn, Gordon C.

2013-01-08

A computer-implemented software self-assembled system and method for providing an external override and monitoring capability to dynamically self-assembling software containing machines that self-assemble execution sequences and data structures. The method provides an external override machine that can be introduced into a system of self-assembling machines while the machines are executing such that the functionality of the executing software can be changed or paused without stopping the code execution and modifying the existing code. Additionally, a monitoring machine can be introduced without stopping code execution that can monitor specified code execution functions by designated machines and communicate the status to an output device.

Transparent crosslinked ultrashort peptide hydrogel dressing with high shape-fidelity accelerates healing of full-thickness excision wounds

KAUST Repository

Seow, Wei Yang; Salgado, Giorgiana; Lane, E. Birgitte; Hauser, Charlotte

2016-01-01

Wound healing is a major burden of healthcare systems worldwide and hydrogel dressings offer a moist environment conducive to healing. We describe cysteine-containing ultrashort peptides that self-assemble spontaneously into hydrogels. After

The free-energy self: a predictive coding account of self-recognition.

Science.gov (United States)

Apps, Matthew A J; Tsakiris, Manos

2014-04-01

Recognising and representing one's self as distinct from others is a fundamental component of self-awareness. However, current theories of self-recognition are not embedded within global theories of cortical function and therefore fail to provide a compelling explanation of how the self is processed. We present a theoretical account of the neural and computational basis of self-recognition that is embedded within the free-energy account of cortical function. In this account one's body is processed in a Bayesian manner as the most likely to be "me". Such probabilistic representation arises through the integration of information from hierarchically organised unimodal systems in higher-level multimodal areas. This information takes the form of bottom-up "surprise" signals from unimodal sensory systems that are explained away by top-down processes that minimise the level of surprise across the brain. We present evidence that this theoretical perspective may account for the findings of psychological and neuroimaging investigations into self-recognition and particularly evidence that representations of the self are malleable, rather than fixed as previous accounts of self-recognition might suggest. Copyright © 2013 Elsevier Ltd. All rights reserved.

How wounds heal

Science.gov (United States)

... How puncture wounds heal; How burns heal; How pressure sores heal; How lacerations heal ... bleed. For example, burns, some puncture wounds, and pressure sores do not bleed. Once the scab forms, your ...

Towards a fragment-based approach in gelator design: halogen effects leading to thixotropic, mouldable and self-healing systems in aryl-triazolyl amino acid-based gelators!

Science.gov (United States)

Srivastava, Bhartendu K; Manheri, Muraleedharan K

2017-04-18

A simple replacement of a H atom by Br transformed non-gelating aryl triazolyl amino acid benzyl ester into a versatile gelator, which formed shape-persistent, self-healing and mouldable gels. The 'bromo-aryl benzyl ester' fragment was then transplanted into another framework, which resulted in similar solvent preference and gelation efficiency.

GRADSPH: A parallel smoothed particle hydrodynamics code for self-gravitating astrophysical fluid dynamics

NARCIS (Netherlands)

Vanaverbeke, S.; Keppens, R.; Poedts, S.; Boffin, H.

2009-01-01

We describe the algorithms implemented in the first version of GRADSPH, a parallel, tree-based, smoothed particle hydrodynamics code for simulating self-gravitating astrophysical systems written in FORTRAN 90. The paper presents details on the implementation of the Smoothed Particle Hydro (SPH)

Intentionality forms the matrix of healing: a theory.

Science.gov (United States)

Zahourek, Rothlyn P

2004-01-01

The understanding of intentionality in a healing context has been incomplete and confusing. Attempts have been made to describe it as a concrete mental force in healing while healing has been accepted as a nonlocal phenomenon. This paper reviews several definitions and theoretical frameworks of intentionality. It proposes a new integrative theory of intentionality, Intentionality: the Matrix of Healing. The theory proposes definitions, forms, and phases of intentionality, a process of development and mediators that sculpt intentionality in healing. The theory has implications for conceptualizing intentionality and provides a framework for continued exploration of the nature of intentionality in healing for scholars as well as clinicians. This study was done as a Doctoral dissertation at New York University, School of Education, Division of Nursing.

Self-healing coatings based on halloysite clay polymer composites for protection of copper alloys.

Science.gov (United States)

Abdullayev, Elshad; Abbasov, Vagif; Tursunbayeva, Asel; Portnov, Vasiliy; Ibrahimov, Hikmat; Mukhtarova, Gulbaniz; Lvov, Yuri

2013-05-22

Halloysite clay nanotubes loaded with corrosion inhibitors benzotriazole (BTA), 2-mercaptobenzimidazole (MBI), and 2-mercaptobenzothiazole (MBT) were used as additives in self-healing composite paint coating of copper. These inhibitors form protective films on the metal surface and mitigate corrosion. Mechanisms involved in the film formation have been studied with optical and electron microscopy, UV-vis spectrometry, and adhesivity tests. Efficiency of the halloysite lumen loading ascended in the order of BTA halloysite formulations have shown the best protection. Inhibitors were kept in the tubes buried in polymeric paint layer for a long time and release was enhanced in the coating defects exposed to humid media with 20-50 h, sufficient for formation of protective layer. Anticorrosive performance of the halloysite-based composite acrylic and polyurethane coatings have been demonstrated for 110-copper alloy strips exposed to 0.5 M aqueous NaCl for 6 months.

Dialing in the Ratio of Covalent and Coordination Cross-links in Self-healing Hydrogels

DEFF Research Database (Denmark)

Andersen, Amanda; Krogsgaard, Marie; Birkedal, Henrik

; it is of great interest to control the degree of which these are present; i.e. controlling the degree of catechol oxidation. Here, we report hydrogels in which the catechols participating in reversible (oxidation resistant catechol-analogue6) and irreversible oxidation cross-links are separated, enabling one...... to predefine the ratio of the two by altering the composition. The oxidation-resistant catechol-analogue was grafted onto polyallylamine,4 while the oxidation cross-links are introduced by addition of tannic acid that has the same useful properties as catechols.5,7,8 This affords hydrogels that retain self......-healing abilities even at high pH but that can be stiffened at will by dialing in the required degree of covalent crosslinking. This dial-in method thus harnesses two aspects of catechol-type chemistries to yield double network hydrogels in a straightforward and highly controllable manner....

The molecular biology in wound healing & non-healing wound.

Science.gov (United States)

Qing, Chun

2017-08-01

The development of molecular biology and other new biotechnologies helps us to recognize the wound healing and non-healing wound of skin in the past 30 years. This review mainly focuses on the molecular biology of many cytokines (including growth factors) and other molecular factors such as extracellular matrix (ECM) on wound healing. The molecular biology in cell movement such as epidermal cells in wound healing was also discussed. Moreover many common chronic wounds such as pressure ulcers, leg ulcers, diabetic foot wounds, venous stasis ulcers, etc. usually deteriorate into non-healing wounds. Therefore the molecular biology such as advanced glycation end products (AGEs) and other molecular factors in diabetes non-healing wounds were also reviewed. Copyright © 2017 Daping Hospital and the Research Institute of Surgery of the Third Military Medical University. Production and hosting by Elsevier B.V. All rights reserved.

On the healing mechanism of sol-gel derived hybrid materials containing dynamic di-sulfide bonds

NARCIS (Netherlands)

AbdolahZadeh, M.; Esteves, A.C.C.; Van der Zwaag, S.; Garcia Espallargas, S.J.

2013-01-01

Sol-gel technology is increasingly being used in coatings for corrosion protection and adhesion improvement. So far, the self-healing concept in sol-gel coatings has only been approached from extrinsic healing perspective (i.e. use of nano and micro carriers of corrosion inhibitors) [1]. Despite the

Performance optimization of PM-16QAM transmission system enabled by real-time self-adaptive coding.

Science.gov (United States)

Qu, Zhen; Li, Yao; Mo, Weiyang; Yang, Mingwei; Zhu, Shengxiang; Kilper, Daniel C; Djordjevic, Ivan B

2017-10-15

We experimentally demonstrate self-adaptive coded 5×100  Gb/s WDM polarization multiplexed 16 quadrature amplitude modulation transmission over a 100 km fiber link, which is enabled by a real-time control plane. The real-time optical signal-to-noise ratio (OSNR) is measured using an optical performance monitoring device. The OSNR measurement is processed and fed back using control plane logic and messaging to the transmitter side for code adaptation, where the binary data are adaptively encoded with three types of low-density parity-check (LDPC) codes with code rates of 0.8, 0.75, and 0.7 of large girth. The total code-adaptation latency is measured to be 2273 ms. Compared with transmission without adaptation, average net capacity improvements of 102%, 36%, and 7.5% are obtained, respectively, by adaptive LDPC coding.

Conducted healing to treat large skin wounds.

Science.gov (United States)

Salgado, M I; Petroianu, A; Alberti, L R; Burgarelli, G L; Barbosa, A J A

2013-01-01

Improvement of the healing process to provide better aesthetical and functional results continues to be a surgical challenge. This study compared the treatment of skin wounds by means of conducted healing (an original method of treatment by secondary healing) and by the use of autogenous skin grafts. Two skin segments, one on each side of the dorsum,were removed from 17 rabbits. The side that served as a graft donor site was left open as to undergo conducted healing (A)and was submitted only to debridement and local care with dressings. The skin removed from the side mentioned above was implanted as a graft (B) to cover the wound on the other side. Thus, each animal received the two types of treatment on its dorsum (A and B). The rabbits were divided into two groups according to the size of the wounds: Group 1 - A and B (4 cm2)and Group 2 - A and B (25 cm2). The healing time was 19 days for Group 1 and 35 days for Group 2. The final macro- and microscopic aspects of the healing process were analysed comparatively among all subgroups. The presence of inflammatory cells, epidermal cysts and of giant cells was evaluated. No macro- or microscopic differences were observed while comparing the wounds that underwent conducted healing and those in which grafting was employed, although the wounds submitted to conducted healing healed more rapidly. Conducted wound healing was effective for the treatment of skin wounds. Celsius.

A Practice-Based Theory of Healing Through Therapeutic Touch: Advancing Holistic Nursing Practice.

Science.gov (United States)

Hanley, Mary Anne; Coppa, Denise; Shields, Deborah

2017-08-01

For nearly 50 years, Therapeutic Touch (TT) has contributed to advancing holistic nursing practice and has been recognized as a uniquely human approach to healing. This narrative explores the development of a practice-based theory of healing through TT, which occurred between 2010 and 2016. Through the in-depth self-inquiry of participatory reflective dialogue in concert with constant narrative analysis, TT practitioners revealed the meaning of healing within the context of their TT practice. As the community of TT experts participated in an iterative process of small group and community dialogues with analysis and synthesis of emerging themes, the assumptions and concepts central to a theory of healing emerged, were clarified and verified. Exemplars of practice illustrate the concepts. A model of the theory of healing illuminates the movement and relationship among concepts and evolved over time. Feedback from nursing and inter-professional practitioners indicate that the theory of healing, while situated within the context of TT, may be useful in advancing holistic nursing practice, informing healing and caring approaches, stimulating research and education, and contributing to future transformations in health care.

Healing and recovering after a suicide attempt: a grounded theory study.

Science.gov (United States)

Chi, Mei-Ting; Long, Ann; Jeang, Shiow-Rong; Ku, Yan-Chiou; Lu, Ti; Sun, Fan-Ko

2014-06-01

To explore the healing and recovery process following a suicide attempt over 12 months ago. Literature has explored the process leading up to attempted suicide. However, there is a lack of information exploring the healing and recovery process after a suicide attempt. Qualitative research using the grounded theory approach. Data were collected during 2010-2011 from the psychiatric outpatient's centre in Taiwan. Interviews were conducted with people who had attempted suicide more than 12 months prior to data collection and had not reattempted since that time (n = 14). Constant comparison analysis was used to scrutinise the data. Findings demonstrated that healing and recovering evolved in five phases: (1) self-awareness: gained self-awareness of their responsibilities in life and their fear of death; (2) the inter-relatedness of life: awareness of the need to seek help from professionals, friends and family for support; (3) the cyclical nature of human emotions: reappearance of stressors and activators causing psyche disharmony; (4) adjustment: changes in adjustment patterns of behaviour, discovering and owning one's own unique emotions, deflecting attention from stressors and facing reality and (5) acceptance: accepting the reality of life and investing in life. The healing and recovery process symbolises an emotional navigation wheel. While each phase might follow the preceding phase, it is not a linear process, and patients might move backwards and forwards through the phases depending on the nursing interventions they receive coupled with their motivation to heal. It is important for nurses to use advanced communication skills to enable them to co-travel therapeutically with patients. Listening to patients' voices and analysing their healing and recovery process could serve as a reference for psychiatric nurses to use to inform therapeutic interventions. © 2013 John Wiley & Sons Ltd.

The perceived effectiveness of traditional and faith healing in the treatment of mental illness: a systematic review of qualitative studies.

Science.gov (United States)

van der Watt, A S J; van de Water, T; Nortje, G; Oladeji, B D; Seedat, S; Gureje, O

2018-04-25

This work complements a quantitative review by Nortje et al. (Lancet Psychiatry 3(2):154-170, 2016) by exploring the qualitative literature in regard to the perceived effectiveness of traditional and faith healing of mental disorders. Qualitative studies focusing specifically on traditional and/or faith healing practices for mental illness were retrieved from eight databases. Data were extracted  into basic coding sheets to facilitate the assessment of the quality of eligible papers using the COREQ. Sixteen articles met the inclusion criteria. Despite methodological limitations, there was evidence from the papers that stakeholders perceived traditional and/or faith healing to be effective in treating mental illness, especially when used in combination with biomedical treatment. Patients will continue to seek treatment from traditional and/or faith healers for mental illness if they perceive it to be effective regardless of alternative biomedical evidence. This provides opportunities for collaboration to address resource scarcity in low to middle income countries.

Analysis of quantum error-correcting codes: Symplectic lattice codes and toric codes

Science.gov (United States)

Harrington, James William

Quantum information theory is concerned with identifying how quantum mechanical resources (such as entangled quantum states) can be utilized for a number of information processing tasks, including data storage, computation, communication, and cryptography. Efficient quantum algorithms and protocols have been developed for performing some tasks (e.g. , factoring large numbers, securely communicating over a public channel, and simulating quantum mechanical systems) that appear to be very difficult with just classical resources. In addition to identifying the separation between classical and quantum computational power, much of the theoretical focus in this field over the last decade has been concerned with finding novel ways of encoding quantum information that are robust against errors, which is an important step toward building practical quantum information processing devices. In this thesis I present some results on the quantum error-correcting properties of oscillator codes (also described as symplectic lattice codes) and toric codes. Any harmonic oscillator system (such as a mode of light) can be encoded with quantum information via symplectic lattice codes that are robust against shifts in the system's continuous quantum variables. I show the existence of lattice codes whose achievable rates match the one-shot coherent information over the Gaussian quantum channel. Also, I construct a family of symplectic self-dual lattices and search for optimal encodings of quantum information distributed between several oscillators. Toric codes provide encodings of quantum information into two-dimensional spin lattices that are robust against local clusters of errors and which require only local quantum operations for error correction. Numerical simulations of this system under various error models provide a calculation of the accuracy threshold for quantum memory using toric codes, which can be related to phase transitions in certain condensed matter models. I also present

Correction: One-step coelectrodeposition-assisted layer-by-layer assembly of gold nanoparticles and reduced graphene oxide and its self-healing three-dimensional nanohybrid for an ultrasensitive DNA sensor.

Science.gov (United States)

Jayakumar, Kumarasamy; Camarada, María Belén; Dharuman, Venkataraman; Ju, Huangxian; Dey, Ramendra Sundar; Wen, Yangping

2018-02-01

Correction for 'One-step coelectrodeposition-assisted layer-by-layer assembly of gold nanoparticles and reduced graphene oxide and its self-healing three-dimensional nanohybrid for an ultrasensitive DNA sensor' by Jayakumar Kumarasamy, et al., Nanoscale, 2018, DOI: 10.1039/c7nr06952a.

The bile acids, deoxycholic acid and ursodeoxycholic acid, regulate colonic epithelial wound healing.

Science.gov (United States)

Mroz, Magdalena S; Lajczak, Natalia K; Goggins, Bridie J; Keely, Simon; Keely, Stephen J

2018-03-01

The intestinal epithelium constitutes an innate barrier which, upon injury, undergoes self-repair processes known as restitution. Although bile acids are known as important regulators of epithelial function in health and disease, their effects on wound healing processes are not yet clear. Here we set out to investigate the effects of the colonic bile acids, deoxycholic acid (DCA) and ursodeoxycholic acid (UDCA), on epithelial restitution. Wound healing in T 84 cell monolayers grown on transparent, permeable supports was assessed over 48 h with or without bile acids. Cell migration was measured in Boyden chambers. mRNA and protein expression were measured by RT-PCR and Western blotting. DCA (50-150 µM) significantly inhibited wound closure in cultured epithelial monolayers and attenuated cell migration in Boyden chamber assays. DCA also induced nuclear accumulation of the farnesoid X receptor (FXR), whereas an FXR agonist, GW4064 (10 µM), inhibited wound closure. Both DCA and GW4064 attenuated the expression of CFTR Cl - channels, whereas inhibition of CFTR activity with either CFTR- inh -172 (10 µM) or GlyH-101 (25 µM) also prevented wound healing. Promoter/reporter assays revealed that FXR-induced downregulation of CFTR is mediated at the transcriptional level. In contrast, UDCA (50-150 µM) enhanced wound healing in vitro and prevented the effects of DCA. Finally, DCA inhibited and UDCA promoted mucosal healing in an in vivo mouse model. In conclusion, these studies suggest bile acids are important regulators of epithelial wound healing and are therefore good targets for development of new drugs to modulate intestinal barrier function in disease treatment. NEW & NOTEWORTHY The secondary bile acid, deoxycholic acid, inhibits colonic epithelial wound healing, an effect which appears to be mediated by activation of the nuclear bile acid receptor, FXR, with subsequent downregulation of CFTR expression and activity. In contrast, ursodeoxycholic acid promotes

Computing Moment-Based Probability Tables for Self-Shielding Calculations in Lattice Codes

International Nuclear Information System (INIS)

Hebert, Alain; Coste, Mireille

2002-01-01

As part of the self-shielding model used in the APOLLO2 lattice code, probability tables are required to compute self-shielded cross sections for coarse energy groups (typically with 99 or 172 groups). This paper describes the replacement of the multiband tables (typically with 51 subgroups) with moment-based tables in release 2.5 of APOLLO2. An improved Ribon method is proposed to compute moment-based probability tables, allowing important savings in CPU resources while maintaining the accuracy of the self-shielding algorithm. Finally, a validation is presented where the absorption rates obtained with each of these techniques are compared with exact values obtained using a fine-group elastic slowing-down calculation in the resolved energy domain. Other results, relative to the Rowland's benchmark and to three assembly production cases, are also presented

Effect of epoxy resin and hardener containing microcapsules on healing efficiency of epoxy adhesive based metal joints

International Nuclear Information System (INIS)

Khan, Nazrul Islam; Halder, Sudipta; Goyat, M.S.

2016-01-01

Dual component microcapsules of epoxy resin and polyamine hardener with polymethyl methacrylate (PMMA) shell were synthesized using a water-oil-water emulsion solvent evaporation method. The high concentration of sodium dodecyl sulfate (SDS) was used to reduce the thickness of shell wall of dual component microcapsules. The dual microcapsules of 1:1 weight ratio were introduced in the epoxy adhesive to study the healing effect. The morphology, chemical structure and thermal characteristics of the microcapsules were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), respectively. The insertion of dual component microcapsules in epoxy matrix reduced the lap shear strength of adhesive joints, which may be attributed to the generation of stress concentration cites because of micron sized capsules. However, the extension and absorbed failure energy of adhesive joints under uniaxial loading increased with the increase of concentration of dual microcapsules. The viscoelastic nature of the dual microcapsules may be responsible for this enhancement. Significant enhancement in the healing efficiency (90.93%) of the joints was achieved for 10 wt% of dual microcapsules. The crack pinning and crack blunting mechanisms at the vicinity of the crack path adjacent to the microcapsules were found responsible for significant enhancement in the healing efficiency of the adhesive joints. - Highlights: • High SDS concentration was used to control the dual component microcapsules shell wall thickness. • Self-healing performance of dual component microcapsules reinforced epoxy adhesive based single lap joints was studied. • 90.93% of the damage healing was achieved for self-healing adhesive based single lap joints. • Increase in concentration of microcapsules reduces the lap shear properties of the self-healing joints.

Effect of epoxy resin and hardener containing microcapsules on healing efficiency of epoxy adhesive based metal joints

Energy Technology Data Exchange (ETDEWEB)

Khan, Nazrul Islam [Department of Mechanical Engineering, National Institute of Technology Silchar, Silchar 788010, Assam (India); Halder, Sudipta, E-mail: shalder@nits.ac.in [Department of Mechanical Engineering, National Institute of Technology Silchar, Silchar 788010, Assam (India); Goyat, M.S. [Department of Physics, University of Petroleum & Energy Studies, Dehradun, Uttarakhand 248007 (India)

2016-03-01

Dual component microcapsules of epoxy resin and polyamine hardener with polymethyl methacrylate (PMMA) shell were synthesized using a water-oil-water emulsion solvent evaporation method. The high concentration of sodium dodecyl sulfate (SDS) was used to reduce the thickness of shell wall of dual component microcapsules. The dual microcapsules of 1:1 weight ratio were introduced in the epoxy adhesive to study the healing effect. The morphology, chemical structure and thermal characteristics of the microcapsules were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), respectively. The insertion of dual component microcapsules in epoxy matrix reduced the lap shear strength of adhesive joints, which may be attributed to the generation of stress concentration cites because of micron sized capsules. However, the extension and absorbed failure energy of adhesive joints under uniaxial loading increased with the increase of concentration of dual microcapsules. The viscoelastic nature of the dual microcapsules may be responsible for this enhancement. Significant enhancement in the healing efficiency (90.93%) of the joints was achieved for 10 wt% of dual microcapsules. The crack pinning and crack blunting mechanisms at the vicinity of the crack path adjacent to the microcapsules were found responsible for significant enhancement in the healing efficiency of the adhesive joints. - Highlights: • High SDS concentration was used to control the dual component microcapsules shell wall thickness. • Self-healing performance of dual component microcapsules reinforced epoxy adhesive based single lap joints was studied. • 90.93% of the damage healing was achieved for self-healing adhesive based single lap joints. • Increase in concentration of microcapsules reduces the lap shear properties of the self-healing joints.

Traditional healing practices in rural Bangladesh: a qualitative investigation.

Science.gov (United States)

Haque, Md Imdadul; Chowdhury, A B M Alauddin; Shahjahan, Md; Harun, Md Golam Dostogir

2018-02-15

Traditional healing practice is an important and integral part of healthcare systems in almost all countries of the world. Very few studies have addressed the holistic scenario of traditional healing practices in Bangladesh, although these serve around 80% of the ailing people. This study explored distinctive forms of traditional healing practices in rural Bangladesh. During July to October 2007, the study team conducted 64 unstructured interviews, and 18 key informant interviews with traditional healers and patients from Bhabanipur and Jobra, two adjacent villages in Chittagong district, Bangladesh. The study also used participatory observations of traditional healing activities in the treatment centers. Majority of the community members, especially people of low socioeconomic status, first approached the traditional healers with their medical problems. Only after failure of such treatment did they move to qualified physicians for modern treatment. Interestingly, if this failed, they returned to the traditional healers. This study identified both religious and non-religious healing practices. The key religious healing practices reportedly included Kalami, Bhandai, and Spiritual Healing, whereas the non-religious healing practices included Sorcery, Kabiraji, and Home Medicine. Both patients and healers practiced self-medication at home with their indigenous knowledge. Kabiraji was widely practiced based on informal use of local medicinal plants in rural areas. Healers in both Kalami and Bhandari practices resorted to religious rituals, and usually used verses of holy books in healing, which required a firm belief of patients for the treatment to be effective. Sorcerers deliberately used their so-called supernatural power not only to treat a patient but also to cause harm to others upon secret request. The spiritual healing reportedly diagnosed and cured the health problems through communication with sacred spirits. Although the fee for diagnosis was small

Kneser-Hecke-operators in coding theory

OpenAIRE

Nebe, Gabriele

2005-01-01

The Kneser-Hecke-operator is a linear operator defined on the complex vector space spanned by the equivalence classes of a family of self-dual codes of fixed length. It maps a linear self-dual code $C$ over a finite field to the formal sum of the equivalence classes of those self-dual codes that intersect $C$ in a codimension 1 subspace. The eigenspaces of this self-adjoint linear operator may be described in terms of a coding-theory analogue of the Siegel $\\Phi $-operator.

Wound Healing and Care

Science.gov (United States)

... Safe Videos for Educators Search English Español Wound Healing and Care KidsHealth / For Teens / Wound Healing and ... open to heal through natural scar formation. The Healing Process Before healing begins, the body gears up ...

Tona, the Folk Healing Practices in Rural Punjab, Pakistan

Directory of Open Access Journals (Sweden)

Azher Hameed Qamar

2016-03-01

Full Text Available Consulting religion and magic for healing is an important aspect of healing belief practices. Magical thinking provides space for culturally cognitive patterns to integrate belief practices. Tona, a layman’s approach to healing that describes magico-religious (fusion of magic and religion and secular magic practices in rural Punjab, Pakistan, is an example of magico-religious and secular magical practice. The purpose of this study is to analyse tona as it is practiced to cure childhood diseases (sokra and sharwa in Muslim Punjab, Pakistan. This is an ethnographic study I conducted using participant observation and unstructured interviews as the primary research methods. The study produced an in-depth analysis of tona as a healing belief practice in the light of Frazer’s principles of magical thinking and sympathetic magic. The study provides a deeper understanding of the magical thinking in magico-religious healing belief practices.

Whiskers growth and self-healing in Ti-based metallic glasses during ion irradiation

Science.gov (United States)

Zhang, Kun; Hu, Zheng; Zhao, Ziqiang; Wei, Bingchen; Li, Yansen; Wei, Yuhang

2018-04-01

Ti-based metallic glasses were subjected to a 20 MeV Cl4+ ion radiation under liquid-nitrogen cooling. Their responses, as well as effects of the electronic excitation and nucleus-nucleus collision were evaluated. The collision cascade during irradiation typically changes the structure by increasing the liquid-like zone/cluster, or the content of the free volume. However, along the ion incident depth, the structure change is inhomogeneous. Numerous whiskers appear and aggregate on the side of the irradiation surface, which are several micrometers away from the edge. This corresponds with the maximum collision depth obtained by the Monte Carlo simulation, where nuclear loss plays a dominant role. Moreover, the liquid-like zone continually forms, which add to the whiskers growth and subsequent self-healing. Results suggest that the irradiation-induced local shear stress combines with the well-localized liquid-like zone results in the observed phenomena. This study demonstrates that metallic glasses have high morphological instability under ion irradiation, which assets can pave new paths for their further applications.

Water-Enabled Healing of Conducting Polymer Films.

Science.gov (United States)

Zhang, Shiming; Cicoira, Fabio

2017-10-01

The conducting polymer polyethylenedioxythiophene doped with polystyrene sulfonate (PEDOT:PSS) has become one of the most successful organic conductive materials due to its high air stability, high electrical conductivity, and biocompatibility. In recent years, a great deal of attention has been paid to its fundamental physicochemical properties, but its healability has not been explored in depth. This communication reports the first observation of mechanical and electrical healability of PEDOT:PSS thin films. Upon reaching a certain thickness (about 1 µm), PEDOT:PSS thin films damaged with a sharp blade can be electrically healed by simply wetting the damaged area with water. The process is rapid, with a response time on the order of 150 ms. Significantly, after being wetted the films are transformed into autonomic self-healing materials without the need of external stimulation. This work reveals a new property of PEDOT:PSS and enables its immediate use in flexible and biocompatible electronics, such as electronic skin and bioimplanted electronics, placing conducting polymers on the front line for healing applications in electronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deep healing: ritual healing in the teshuvah movement.

Science.gov (United States)

Sharabi, Asaf

2014-12-01

Based on an ethnographic analysis of religious healing rituals in Israel, this paper addresses the question of how healer-client relations are structured on these rituals. An examination of what takes place at the rallies held by Rabbi Amnon Yitzhak indicates that, apart from the regular blessings, which can be referred to as ordinary healing, there are some ritual events that can be referred to as 'deep healing'. The current paper demonstrates how deep healing rituals are generally conducted in severe cases through give-and-take between the rabbi and the person upon whom the blessing is bestowed, and that they are linked to relationships between people and the ethic of mutual support.

A self-healable and highly stretchable supercapacitor based on a dual crosslinked polyelectrolyte

Science.gov (United States)

Huang, Yan; Zhong, Ming; Huang, Yang; Zhu, Minshen; Pei, Zengxia; Wang, Zifeng; Xue, Qi; Xie, Xuming; Zhi, Chunyi

2015-12-01

Superior self-healability and stretchability are critical elements for the practical wide-scale adoption of personalized electronics such as portable and wearable energy storage devices. However, the low healing efficiency of self-healable supercapacitors and the small strain of stretchable supercapacitors are fundamentally limited by conventional polyvinyl alcohol-based acidic electrolytes, which are intrinsically neither self-healable nor highly stretchable. Here we report an electrolyte comprising polyacrylic acid dual crosslinked by hydrogen bonding and vinyl hybrid silica nanoparticles, which displays all superior functions and provides a solution to the intrinsic self-healability and high stretchability problems of a supercapacitor. Supercapacitors with this electrolyte are non-autonomic self-healable, retaining the capacitance completely even after 20 cycles of breaking/healing. These supercapacitors are stretched up to 600% strain with enhanced performance using a designed facile electrode fabrication procedure.

Providence and God�s emergent will through prayer as it relates to determinism and healing

Directory of Open Access Journals (Sweden)

M Pretorius

2007-09-01

Full Text Available The paper has a twofold purpose. The first is to explore: if God has settled His plans and He will do what He is going to do, then does it matter whether one prays or not? This section will also deal with the aspect of healing and prayer, specifically from a scientific perspective. The important question is: How should one treat reports of miraculous healings, and the� belief that prayer can affect healing? Secondly, if prayer has any effect on what happens, then it would seem that God� s plans are not fixed in the first place, and then the idea of an open-future would seem to be valid. As a result, one could no longer see the world as a mechanistic Newtonian picture. Rather , the picture portrayed would be of a world of flexibility and openness to change. The question would then be: What is the manner and scope of divine action and wherein lies the causal joint? Regarding this, areas related to determinism will be explored as determinism states that all events in the world are the result of some previous event, or events. Bringing� clarity to these questions is important, as is it has a direct bearing on how one will view miracles recorded in the Scriptures, and how far one will go in trusting God to meet one� s needs through prayer.

Biologically inspired autonomous structural materials with controlled toughening and healing

Science.gov (United States)

Garcia, Michael E.; Sodano, Henry A.

2010-04-01

The field of structural health monitoring (SHM) has made significant contributions in the field of prognosis and damage detection in the past decade. The advantageous use of this technology has not been integrated into operational structures to prevent damage from propagating or to heal injured regions under real time loading conditions. Rather, current systems relay this information to a central processor or human operator, who then determines a course of action such as altering the mission or scheduling repair maintenance. Biological systems exhibit advanced sensory and healing traits that can be applied to the design of material systems. For instance, bone is the major structural component in vertebrates; however, unlike modern structural materials, bone has many properties that make it effective for arresting the propagation of cracks and subsequent healing of the fractured area. The foremost goal for the development of future adaptive structures is to mimic biological systems, similar to bone, such that the material system can detect damage and deploy defensive traits to impede damage from propagating, thus preventing catastrophic failure while in operation. After sensing and stalling the propagation of damage, the structure must then be repaired autonomously using self healing mechanisms motivated by biological systems. Here a novel autonomous system is developed using shape memory polymers (SMPs), that employs an optical fiber network as both a damage detection sensor and a network to deliver stimulus to the damage site initiating adaptation and healing. In the presence of damage the fiber optic fractures allowing a high power laser diode to deposit a controlled level of thermal energy at the fractured sight locally reducing the modulus and blunting the crack tip, which significantly slows the crack growth rate. By applying a pre-induced strain field and utilizing the shape memory recovery effect, thermal energy can be deployed to close the crack and return

New Improvements in Mixture Self-Shielding Treatment with APOLLO2 Code

International Nuclear Information System (INIS)

Coste-Delclaux, M.

2006-01-01

Full text of the presentation follows: APOLLO2 is a modular multigroup transport code developed at the CEA in Saclay (France). Previously, the self-shielding module could only treat one resonant isotope mixed with moderator isotopes. Consequently, the resonant mixture self-shielding treatment was an iterative one. Each resonant isotope of the mixture was treated separately, the other resonant isotopes of the mixture being then considered as moderator isotopes, that is to say non-resonant isotopes. This treatment could be iterated. Recently, we have developed a new method that consists in treating the resonant mixture as a unique entity. A main feature of APOLLO2 self-shielding module is that some implemented models are very general and therefore very powerful and versatile. We can give, as examples, the use of probability tables in order to describe the microscopic cross-section fluctuations or the TR slowing-down model that can deal with any resonance shape. The self-shielding treatment of a resonant mixture was developed essentially thanks to these two models. The goal of this paper is to describe the improvements on the self-shielding treatment of a resonant mixture and to present, as an application, the calculation of the ATRIUM-10 BWR benchmark. We will conclude by some prospects on remaining work in the self-shielding domain. (author)

Insights into the key roles of epigenetics in matrix macromolecules-associated wound healing.

Science.gov (United States)

Piperigkou, Zoi; Götte, Martin; Theocharis, Achilleas D; Karamanos, Nikos K

2017-10-24

Extracellular matrix (ECM) is a dynamic network of macromolecules, playing a regulatory role in cell functions, tissue regeneration and remodeling. Wound healing is a tissue repair process necessary for the maintenance of the functionality of tissues and organs. This highly orchestrated process is divided into four temporally overlapping phases, including hemostasis, inflammation, proliferation and tissue remodeling. The dynamic interplay between ECM and resident cells exerts its critical role in many aspects of wound healing, including cell proliferation, migration, differentiation, survival, matrix degradation and biosynthesis. Several epigenetic regulatory factors, such as the endogenous non-coding microRNAs (miRNAs), are the drivers of the wound healing response. microRNAs have pivotal roles in regulating ECM composition during wound healing and dermal regeneration. Their expression is associated with the distinct phases of wound healing and they serve as target biomarkers and targets for systematic regulation of wound repair. In this article we critically present the importance of epigenetics with particular emphasis on miRNAs regulating ECM components (i.e. glycoproteins, proteoglycans and matrix proteases) that are key players in wound healing. The clinical relevance of miRNA targeting as well as the delivery strategies designed for clinical applications are also presented and discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

URR [Unresolved Resonance Region] computer code: A code to calculate resonance neutron cross-section probability tables, Bondarenko self-shielding factors, and self-indication ratios for fissile and fertile nuclides

International Nuclear Information System (INIS)

Leal, L.C.; de Saussure, G.; Perez, R.B.

1989-01-01

The URR computer code has been developed to calculate cross-section probability tables, Bondarenko self-shielding factors, and self- indication ratios for fertile and fissile isotopes in the unresolved resonance region. Monte Carlo methods are utilized to select appropriate resonance parameters and to compute the cross sections at the desired reference energy. The neutron cross sections are calculated by the single-level Breit-Wigner formalism with s-, p-, and d-wave contributions. The cross-section probability tables are constructed by sampling the Doppler broadened cross-section. The various shelf-shielded factors are computed numerically as Lebesgue integrals over the cross-section probability tables. 6 refs

Biomaterials and Nanotherapeutics for Enhancing Skin Wound Healing

Science.gov (United States)

Das, Subhamoy; Baker, Aaron B.

2016-01-01

Wound healing is an intricate process that requires complex coordination between many cell types and an appropriate extracellular microenvironment. Chronic wounds often suffer from high protease activity, persistent infection, excess inflammation, and hypoxia. While there has been intense investigation to find new methods to improve cutaneous wound care, the management of chronic wounds, burns, and skin wound infection remain challenging clinical problems. Ideally, advanced wound dressings can provide enhanced healing and bridge the gaps in the healing processes that prevent chronic wounds from healing. These technologies have great potential for improving outcomes in patients with poorly healing wounds but face significant barriers in addressing the heterogeneity and clinical complexity of chronic or severe wounds. Active wound dressings aim to enhance the natural healing process and work to counter many aspects that plague poorly healing wounds, including excessive inflammation, ischemia, scarring, and wound infection. This review paper discusses recent advances in the development of biomaterials and nanoparticle therapeutics to enhance wound healing. In particular, this review focuses on the novel cutaneous wound treatments that have undergone significant preclinical development or are currently used in clinical practice. PMID:27843895

Biomaterials and Nanotherapeutics for Enhancing Skin Wound Healing

Directory of Open Access Journals (Sweden)

Subhamoy Das

2016-10-01

Full Text Available Wound healing is an intricate process that requires complex coordination between many cells and an appropriate extracellular microenvironment. Chronic wounds often suffer from high protease activity, persistent infection, excess inflammation, and hypoxia. While there has been intense investigation to find new methods to improve cutaneous wound care; the management of chronic wounds, burns, and skin wound infection remain challenging clinical problems. Ideally, advanced wound dressings can provide enhanced healing and bridge the gaps in the healing processes that prevent chronic wounds from healing. These technologies have great potential for improving outcomes in patients with poorly healing wounds but face significant barriers in addressing the heterogeneity and clinical complexity of chronic or severe wounds. Active wound dressings aim to enhance the natural healing process and work to counter many aspects that plague poorly healing wounds including excessive inflammation, ischemia, scarring and wound infection. This review paper discusses recent advances in the development of biomaterials and nanoparticle therapeutics to enhance wound healing. In particular, this review focuses on the novel cutaneous wound treatments that have undergone significant preclinical development or currently used in clinical practice.

Issues in Developing a Surveillance Case Definition for Nonfatal Suicide Attempt and Intentional Self-harm Using International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) Coded Data.

Science.gov (United States)

Hedegaard, Holly; Schoenbaum, Michael; Claassen, Cynthia; Crosby, Alex; Holland, Kristin; Proescholdbell, Scott

2018-02-01

Suicide and intentional self-harm are among the leading causes of death in the United States. To study this public health issue, epidemiologists and researchers often analyze data coded using the International Classification of Diseases (ICD). Prior to October 1, 2015, health care organizations and providers used the clinical modification of the Ninth Revision of ICD (ICD-9-CM) to report medical information in electronic claims data. The transition in October 2015 to use of the clinical modification of the Tenth Revision of ICD (ICD-10-CM) resulted in the need to update methods and selection criteria previously developed for ICD-9-CM coded data. This report provides guidance on the use of ICD-10-CM codes to identify cases of nonfatal suicide attempts and intentional self-harm in ICD-10-CM coded data sets. ICD-10-CM codes for nonfatal suicide attempts and intentional self-harm include: X71-X83, intentional self-harm due to drowning and submersion, firearms, explosive or thermal material, sharp or blunt objects, jumping from a high place, jumping or lying in front of a moving object, crashing of motor vehicle, and other specified means; T36-T50 with a 6th character of 2 (except for T36.9, T37.9, T39.9, T41.4, T42.7, T43.9, T45.9, T47.9, and T49.9, which are included if the 5th character is 2), intentional self-harm due to drug poisoning (overdose); T51-T65 with a 6th character of 2 (except for T51.9, T52.9, T53.9, T54.9, T56.9, T57.9, T58.0, T58.1, T58.9, T59.9, T60.9, T61.0, T61.1, T61.9, T62.9, T63.9, T64.0, T64.8, and T65.9, which are included if the 5th character is 2), intentional self-harm due to toxic effects of nonmedicinal substances; T71 with a 6th character of 2, intentional self-harm due to asphyxiation, suffocation, strangulation; and T14.91, Suicide attempt. Issues to consider when selecting records for nonfatal suicide attempts and intentional self-harm from ICD-10-CM coded administrative data sets are also discussed. All material appearing in this

Bioinspired Ultratough Hydrogel with Fast Recovery, Self-Healing, Injectability and Cytocompatibility.

Science.gov (United States)

Azevedo, Sara; Costa, Ana M S; Andersen, Amanda; Choi, Insung S; Birkedal, Henrik; Mano, João F

2017-07-01

Inspired by the mussel byssus adhesiveness, a highly hydrated polymeric structure is designed to combine, for the first time, a set of interesting features for load-bearing purposes. These characteristics include: i) a compressive strength and stiffness in the MPa range, ii) toughness and the ability to recover it upon successive cyclic loading, iii) the ability to quickly self-heal upon rupture, iv) the possibility of administration through minimally invasive techniques, such as by injection, v) the swelling ratio being adjusted to space-filling applications, and vi) cytocompatibility. Owing to these characteristics and the mild conditions employed, the encapsulation of very unstable and sensitive cargoes is possible, highlighting their potential to researchers in the biomedical field for the repair of load-bearing soft tissues, or to be used as an encapsulation platform for a variety of biological applications such as disease models for drug screening and therapies in a more realistic mechanical environment. Moreover, given the simplicity of this methodology and the enhanced mechanical performance, this strategy can be expanded to applications in other fields, such as agriculture and electronics. As such, it is anticipated that the proposed strategy will constitute a new, versatile, and cost-effective tool to produce engineered polymeric structures for both science and technology. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Puerto Rican kindergartners' self-worth as coded from the Attachment Story Completion Task: correlated with other self-evaluation measures and ratings of child behavior toward mothers and peers.

Science.gov (United States)

Gullón-Rivera, Ángel L

2013-01-01

This multi-method multi-informant study assessed 105 Puerto Rican kindergartners' sense of self-worth in family relationships as coded from their responses to the Attachment Story Completion Task (ASCT). The ASCT scores were compared with responses to two other age-appropriate self-evaluation measures (the Cassidy Puppet Interview and the Pictorial Scales of Social Acceptance). Correlations of children's scores on the three self-measures with maternal ratings of the mother-child relationship and teacher ratings of the child's prosocial behavior with peers were then compared. ASCT self-worth and Puppet Interview scores were strongly correlated with each other and both were modestly related to the pictorial social acceptance scales. All three measures were significantly associated with maternal and teacher reports of child behavior, but the strongest correlations were obtained with the ASCT. Coding the ASCT in terms of self-worth appears to be a promising approach for evaluating young children's (vicariously expressed) self-worth in family relationships.

Smart Electrochemical Energy Storage Devices with Self-Protection and Self-Adaptation Abilities.

Science.gov (United States)

Yang, Yun; Yu, Dandan; Wang, Hua; Guo, Lin

2017-12-01

Currently, with booming development and worldwide usage of rechargeable electrochemical energy storage devices, their safety issues, operation stability, service life, and user experience are garnering special attention. Smart and intelligent energy storage devices with self-protection and self-adaptation abilities aiming to address these challenges are being developed with great urgency. In this Progress Report, we highlight recent achievements in the field of smart energy storage systems that could early-detect incoming internal short circuits and self-protect against thermal runaway. Moreover, intelligent devices that are able to take actions and self-adapt in response to external mechanical disruption or deformation, i.e., exhibiting self-healing or shape-memory behaviors, are discussed. Finally, insights into the future development of smart rechargeable energy storage devices are provided. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Induction healing of concrete reinforced by bitumen-coated steel fibres

NARCIS (Netherlands)

Romero Rodriguez, C.; Chaves Figueiredo, S.; Chiaia, B.; Schlangen, H.E.J.G.; Saouma, V.; Bolander, J.; Landis, E.

2016-01-01

Cracking in concrete structures compromises the durability and functionality of the structures themselves. Different kinds of self-healing concretes, less or more sophisticated, have been developed in the past ten years to overcome early cracks in structures. An experimental study of a novel

A Transpersonal Theory of Healing Following Youth Suicide

Science.gov (United States)

Kalischuk, Ruth Grant; Nixon, Gary

2009-01-01

Youth suicide is a complex and perplexing public health problem. This article presents a brief overview of related literature, describes a transpersonal theory of healing following youth suicide, and provides practice implications. Individual healing is conceptually described as a transpersonal journey characterized by the inter-relationships…

Capsules with evolving brittleness to resist the preparation of self-healing concrete

Directory of Open Access Journals (Sweden)

Gruyaert, E.

2016-09-01

Full Text Available Capsules for self-healing concrete have to possess multifunctional properties and it would be an enormous advantage in the valorization process when they could also be mixed in. Therefore, we aimed to develop capsules with evolving brittleness. Capsules with high initial flexibility were prepared by adding a plasticizer to an ethyl cellulose matrix. During hardening of the concrete, the plasticizing agent should leach out to the moist environment yielding more brittle capsules which break upon crack appearance. The tested capsules could easily be mixed in during concrete production. However, incompatibility issues between the capsule wall and the inner polymeric healing agent appeared. Moreover, the capsules became insufficiently brittle and the bond strength to the cementitious matrix was too weak. Consequently, multilayer capsules were tested. These capsules had a high impact resistance to endure concrete mixing and were able to break upon crack formation.Las cápsulas para la auto-reparación del hormigón tienen que poseer propiedades multifuncionales. Una enorme ventaja en el proceso para su valorización se obtendría si aquellas pudieran resistir con éxito el mezclado. Por lo tanto, nos propusimos desarrollar cápsulas cuya fragilidad evoluciona. Cápsulas con una alta flexibilidad inicial se prepararon mediante la adición de un plastificante a una matriz de etil celulosa. Durante el endurecimiento del hormigón, el agente plastificante debe filtrarse hacia el medio ambiente húmedo produciendo cápsulas más frágiles que se rompen con el surgimiento de fisuras. Las cápsulas pudieron ser fácilmente mezcladas durante la producción de hormigón. Sin embargo, aparecieron problemas de incompatibilidad entre la pared de la cápsula y el agente de curación polimérico interior. Por otra parte, las cápsulas se comportaron insuficientemente frágiles y con una baja adherencia hacia la matriz cementicia. En consecuencia, se probaron las c

A numerical study into the effects of elongated capsules on the healing efficiency of liquid-based systems

NARCIS (Netherlands)

Mookhoek, S.D.; Fischer, H.R.; Zwaag, S. van der

2009-01-01

In this numerical study the release of healing agent for liquid-based self-healing systems for elongated microcapsules is studied and compared with that for the usual spherical capsules. It is shown that a high aspect ratio and a proper spatial orientation of the elongated capsules have a positive

A fortran code CVTRAN to provide cross-section file for TWODANT by using macroscopic file written by SRAC

International Nuclear Information System (INIS)

Yamane, Tsuyoshi; Tsuchihashi, Keichiro

1999-03-01

A code CVTRAN provides the macroscopic cross-sections in the format of XSLIB file which is one of Standard interface files for a two-dimensional Sn transport code TWODANT by reading a macroscopic cross section file in the PDS format which is prepared by SRAC execution. While a two-dimensional Sn transport code TWOTRAN published by LANL is installed as a module in the SRAC code system, several functions such as alpha search, concentration search, zone thickness search and various edits are suppressed. Since the TWODANT code was released from LANL, its short running time, stable convergence and plenty of edits have attracted many users. The code CVTRAN makes the TWODANT available to the SRAC user by providing the macroscopic cross-sections on a card-image file XSLIB. The CVTRAN also provides material dependent fission spectra into a card-image format file CVLIB, together with group velocities, group boundary energies and material names. The user can feed them into the TWODANT input, if necessary, by cut-and-paste command. (author)

The molecular signature of impaired diabetic wound healing identifies serpinB3 as a healing biomarker.

Science.gov (United States)

Fadini, Gian Paolo; Albiero, Mattia; Millioni, Renato; Poncina, Nicol; Rigato, Mauro; Scotton, Rachele; Boscari, Federico; Brocco, Enrico; Arrigoni, Giorgio; Villano, Gianmarco; Turato, Cristian; Biasiolo, Alessandra; Pontisso, Patrizia; Avogaro, Angelo

2014-09-01

Chronic foot ulceration is a severe complication of diabetes, driving morbidity and mortality. The mechanisms underlying delaying wound healing in diabetes are incompletely understood and tools to identify such pathways are eagerly awaited. Wound biopsies were obtained from 75 patients with diabetic foot ulcers. Matched subgroups of rapidly healing (RH, n = 17) and non-healing (NH, n = 11) patients were selected. Proteomic analysis was performed by labelling with isobaric tag for relative and absolute quantification and mass spectrometry. Differentially expressed proteins were analysed in NH vs RH for identification of pathogenic pathways. Individual sample gene/protein validation and in vivo validation of candidate pathways in mouse models were carried out. Pathway analyses were conducted on 92/286 proteins that were differentially expressed in NH vs RH. The following pathways were enriched in NH vs RH patients: apoptosis, protease inhibitors, epithelial differentiation, serine endopeptidase activity, coagulation and regulation of defence response. SerpinB3 was strongly upregulated in RH vs NH wounds, validated as protein and mRNA in individual samples. To test the relevance of serpinB3 in vivo, we used a transgenic mouse model with α1-antitrypsin promoter-driven overexpression of human SERPINB3. In this model, wound healing was unaffected by SERPINB3 overexpression in non-diabetic or diabetic mice with or without hindlimb ischaemia. In an independent validation cohort of 47 patients, high serpinB3 protein content was confirmed as a biomarker of healing improvement. We provide a benchmark for the unbiased discovery of novel molecular targets and biomarkers of impaired diabetic wound healing. High serpinB3 protein content was found to be a biomarker of successful healing in diabetic patients.

Kids’ Perceptions toward Children’s Ward Healing Environments: A Case Study of Taiwan University Children’s Hospital

Directory of Open Access Journals (Sweden)

Jeng-Chung Woo

2016-01-01

Full Text Available This paper summarizes the opinions of experts who participated in designing the environment of a children’s hospital and reports the results of a questionnaire survey conducted among hospital users. The grounded theory method was adopted to analyze 292 concepts, 79 open codes, 25 axial codes, and 4 selective codes; in addition, confirmatory factor analysis and reliability analysis were performed to identify elements for designing a healing environment in a children’s hospital, and 21 elements from 4 dimensions, namely, emotions, space design, interpersonal interaction, and pleasant surroundings, were determined. Subsequently, this study examined the perceptions of 401 children at National Taiwan University Children’s Hospital. The results revealed that, regarding the children’s responses to the four dimensions and their overall perception, younger children accepted the healing environment to a significantly higher degree than did older children. The sex effect was significant for the space design dimension, and it was not significant for the other dimensions.

Health-Related Quality of Life Predicts Major Amputation and Death, but Not Healing, in People With Diabetes Presenting With Foot Ulcers

DEFF Research Database (Denmark)

Siersma, V.; Thorsen, H.; Holstein, P.E.

2014-01-01

healing, major amputation and death.Research design and methodsWe followed 1088 patients with new diabetic foot ulcers presenting for treatment at one of the 14 centers in 10 European countries participating in the Eurodiale study, prospectively until healing (76.9%), major amputation (4.6%) or death (6...... for major amputation (Mobility, Self-Care, Usual Activities) and death (Self-care, Usual Activities, Pain/Discomfort).ConclusionsLow HRQoL appears to be predictive for major amputation and death, but high HRQoL does not increase healing. Future studies into the influence of HRQoL on ulcer outcome...

Resonance self-shielding methodology of new neutron transport code STREAM

International Nuclear Information System (INIS)

Choi, Sooyoung; Lee, Hyunsuk; Lee, Deokjung; Hong, Ser Gi

2015-01-01

This paper reports on the development and verification of three new resonance self-shielding methods. The verifications were performed using the new neutron transport code, STREAM. The new methodologies encompass the extension of energy range for resonance treatment, the development of optimum rational approximation, and the application of resonance treatment to isotopes in the cladding region. (1) The extended resonance energy range treatment has been developed to treat the resonances below 4 eV of three resonance isotopes and shows significant improvements in the accuracy of effective cross sections (XSs) in that energy range. (2) The optimum rational approximation can eliminate the geometric limitations of the conventional approach of equivalence theory and can also improve the accuracy of fuel escape probability. (3) The cladding resonance treatment method makes it possible to treat resonances in cladding material which have not been treated explicitly in the conventional methods. These three new methods have been implemented in the new lattice physics code STREAM and the improvement in the accuracy of effective XSs is demonstrated through detailed verification calculations. (author)

A Study on Emotional Healing Efficacy of Fiction for Undergraduate

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Chen Su-May Sheih

2014-01-01

Full Text Available In modern society, undergraduates may encounter multiple pressures and thus feel the sense of alienation, anxiety, disturbance and depression. For undergraduates, reading can be independently conducted without the intervention of an instructor; therefore, undergraduates who feel reluctant to expose private emotions to counselors can help themselves through the reading of emotional healing books. This is the application of bibliotherapy. Among various resources, fiction can serve as an appropriate emotional reading material. The researcher deployed semi-structured in-depth interview, and interviewed 21 undergraduates in Taipei City and Taipei County. This study is aimed to understand the kinds of fictions undergraduates read when they are upset and to analyze the emotional healing process of identification, catharsis, and insight so that the emotional healing efficacy can be evaluated. The findings showed that romance, realistic fiction, fantasy, martial arts novel, inspirational fiction, historical fiction, and science fiction can provide full process of emotional healing efficacy. However, detective fiction, online novel, psychological fiction, and horror fiction can only provide parts of the healing process. Besides, the healing efficacy of a specific fiction is different from reader to reader.

Codon Distribution in Error-Detecting Circular Codes

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Elena Fimmel

2016-03-01

Full Text Available In 1957, Francis Crick et al. suggested an ingenious explanation for the process of frame maintenance. The idea was based on the notion of comma-free codes. Although Crick’s hypothesis proved to be wrong, in 1996, Arquès and Michel discovered the existence of a weaker version of such codes in eukaryote and prokaryote genomes, namely the so-called circular codes. Since then, circular code theory has invariably evoked great interest and made significant progress. In this article, the codon distributions in maximal comma-free, maximal self-complementary C3 and maximal self-complementary circular codes are discussed, i.e., we investigate in how many of such codes a given codon participates. As the main (and surprising result, it is shown that the codons can be separated into very few classes (three, or five, or six with respect to their frequency. Moreover, the distribution classes can be hierarchically ordered as refinements from maximal comma-free codes via maximal self-complementary C3 codes to maximal self-complementary circular codes.

Codon Distribution in Error-Detecting Circular Codes.

Science.gov (United States)

Fimmel, Elena; Strüngmann, Lutz

2016-03-15

In 1957, Francis Crick et al. suggested an ingenious explanation for the process of frame maintenance. The idea was based on the notion of comma-free codes. Although Crick's hypothesis proved to be wrong, in 1996, Arquès and Michel discovered the existence of a weaker version of such codes in eukaryote and prokaryote genomes, namely the so-called circular codes. Since then, circular code theory has invariably evoked great interest and made significant progress. In this article, the codon distributions in maximal comma-free, maximal self-complementary C³ and maximal self-complementary circular codes are discussed, i.e., we investigate in how many of such codes a given codon participates. As the main (and surprising) result, it is shown that the codons can be separated into very few classes (three, or five, or six) with respect to their frequency. Moreover, the distribution classes can be hierarchically ordered as refinements from maximal comma-free codes via maximal self-complementary C(3) codes to maximal self-complementary circular codes.

Identification of a genetic variant associated with rotator cuff repair healing.

Science.gov (United States)

Tashjian, Robert Z; Granger, Erin K; Zhang, Yue; Teerlink, Craig C; Cannon-Albright, Lisa A

2016-06-01

A familial and genetic predisposition for the development of rotator cuff tearing has been identified. The purpose of this study was to determine if a familial predisposition exists for healing after rotator cuff repair and if the reported significant association with a single-nucleotide polymorphism (SNP) in the ESRRB gene is present in patients who fail to heal. The study recruited 72 patients undergoing arthroscopic rotator cuff repair for a full-thickness posterosuperior tear. Magnetic resonance imaging studies were performed at a minimum of 1 year postoperatively (average, 2.6 years). Healing failures were classified as lateral or medial. Self-reported family history of rotator cuff tearing data and genome-wide genotypes were available. Characteristics of cases with and without a family history of rotator cuff tearing were compared, and a comparison of the frequency of SNP 1758384 (in ESRRB) was performed between patients who healed and those who failed to heal. Of the rotator cuff repairs, 42% failed to heal; 42% of patients reported a family history of rotator cuff tear. Multivariate regression analysis showed a significant association between familiality and overall healing failure (medial and lateral failures) (P = .036) and lateral failures independently (P = .006). An increased risk for the presence of a rare allele for SNP rs17583842 was present in lateral failures compared with those that healed (P = .005). Individuals with a family history of rotator cuff tearing were more likely to have repair failures. Significant association of a SNP variant in the ESRRB gene was also observed with lateral failure. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Microcapsules Filled with a Palm Oil-Based Alkyd as Healing Agent for Epoxy Matrix

OpenAIRE

Nurshafiza Shahabudin; Rosiyah Yahya; Seng Neon Gan

2016-01-01

One of the approaches to prolong the service lifespan of polymeric material is the development of self-healing ability by means of embedded microcapsules containing a healing agent. In this work, poly(melamine-urea-formaldehyde) (PMUF) microcapsules containing a palm oil-based alkyd were produced by polymerization of melamine resin, urea and formaldehyde that encapsulated droplets of the suspended alkyd particles. A series of spherical and free-flowing microcapsules were obtained. The chemica...

New Guar Biopolymer Silver Nanocomposites for Wound Healing Applications

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Runa Ghosh Auddy

2013-01-01

Full Text Available Wound healing is an innate physiological response that helps restore cellular and anatomic continuity of a tissue. Selective biodegradable and biocompatible polymer materials have provided useful scaffolds for wound healing and assisted cellular messaging. In the present study, guar gum, a polymeric galactomannan, was intrinsically modified to a new cationic biopolymer guar gum alkylamine (GGAA for wound healing applications. Biologically synthesized silver nanoparticles (Agnp were further impregnated in GGAA for extended evaluations in punch wound models in rodents. SEM studies showed silver nanoparticles well dispersed in the new guar matrix with a particle size of ~18 nm. In wound healing experiments, faster healing and improved cosmetic appearance were observed in the new nanobiomaterial treated group compared to commercially available silver alginate cream. The total protein, DNA, and hydroxyproline contents of the wound tissues were also significantly higher in the treated group as compared with the silver alginate cream (P<0.05. Silver nanoparticles exerted positive effects because of their antimicrobial properties. The nanobiomaterial was observed to promote wound closure by inducing proliferation and migration of the keratinocytes at the wound site. The derivatized guar gum matrix additionally provided a hydrated surface necessary for cell proliferation.

Quantum computation with topological codes from qubit to topological fault-tolerance

CERN Document Server

Fujii, Keisuke

2015-01-01

This book presents a self-consistent review of quantum computation with topological quantum codes. The book covers everything required to understand topological fault-tolerant quantum computation, ranging from the definition of the surface code to topological quantum error correction and topological fault-tolerant operations. The underlying basic concepts and powerful tools, such as universal quantum computation, quantum algorithms, stabilizer formalism, and measurement-based quantum computation, are also introduced in a self-consistent way. The interdisciplinary fields between quantum information and other fields of physics such as condensed matter physics and statistical physics are also explored in terms of the topological quantum codes. This book thus provides the first comprehensive description of the whole picture of topological quantum codes and quantum computation with them.

The significance of belief and expectancy within the spiritual healing encounter.

Science.gov (United States)

Wirth, D P

1995-07-01

effective treatment protocol for severe or long-term disorders. An important contributing feature of this study was that an independent means of assessing the patients' self-reports, i.e. an allopathic medical examination, was included in the experiment. There was a significant correlation between the patient's expectation level and their assessment of improvement, as well as a significant relationship between the patient's assessment of their condition and the objective evaluations provided by independent medical examinations.

Study of transfers and their interactions with self-healing in the cracks to increase the service life of infrastructures (bridges, nuclear centrals); Etude des transferts et de leurs interactions avec la cicatrisation dans les fissures pour prolonger la duree de service des infrastructures (ponts, centrales nucleaires)

Energy Technology Data Exchange (ETDEWEB)

Ismail, M

2006-04-15

Concrete structures are frequently cracked by the action of different types of physicochemical mechanisms (external loads, restrained shrinkage, internal expansion). Cracks could impair the durability of concrete structures by creating preferential paths for the penetration of various types of potentially aggressive agents (liquids, gases, and ions). The aim of this thesis is to study transport properties in mechanically induced cracks. The first objective of the study is to better understand the potential effect of critical crack opening and self-healing. Cracks were generated in an inert material (brick) and in old mortar samples of 28 days and 2 years of age. A mechanical expansive core was used to generate cracks of constant width across the thickness of the sample. For the brick material, results show that a mechanical interaction between the fracture surfaces (critical crack opening) can affect the chloride-diffusion process along a crack path. A critical crack opening was also found for mortar samples. The age at which cracks were generated is also an important parameter. Self-healing was found to be more important in young mortars (28 days). The second objective of this thesis is the prediction of airflow in cracked cementitious material samples. A model proposed by Rizkalla et al. was evaluated through the experimental measurement of the flow coefficient n and the friction coefficient k. A simplified model was proposed to predict airflow through a crack for laminar type flow. The third research objective is to study the effect of self-healing on airflow through cracked mortar samples stored in a 100% relative humidity environment. Results show that self-healing mainly occurs during the first two months of storage. SEM analysis of fracture surfaces shows the formation of self-healing products such as calcite, C-S-H, and ettringite. (author)

Self-healing polymer cement composites for geothermal wellbore applications

Science.gov (United States)

Rod, K. A.; Fernandez, C.; Childers, I.; Koech, P.; Um, W.; Roosendaal, T.; Nguyen, M.; Huerta, N. J.; Chun, J.; Glezakou, V. A.

2017-12-01

Cement is vital for controlling leaks from wellbores employed in oil, gas, and geothermal operations by sealing the annulus between the wellbore casing and geologic formation. Wellbore cement failure due to physical and chemical stresses is common and can result in significant environmental consequences and ultimately significant financial costs due to remediation efforts. To date numerous alternative cement blends have been proposed for the oil and gas industry. Most of these possess poor mechanical properties, or are not designed to work in high temperature environments. This research investigates novel polymer-cement composites which could function at most geothermal temperatures. Thermal stability and mechanical strength of the polymer is attributed to the formation of a number of chemical interactions between the polymer and cement matrix including covalent bonds, hydrogen bonding, and van der Waals interactions. It has been demonstrated that the bonding between cement and casing is more predictable when polymer is added to cement and can even improve healing of adhesion break when subjected to stresses such as thermal shock. Fractures have also been healed, effectively reducing permeability with fractures up to 0.3-0.5mm apertures, which is two orders of magnitude larger than typical wellbore fractures. Additionally, tomography analysis was used to determine internal structure of the cement polymer composite and imaging reveals that polymers fill fractures in the cement and between the cement and casing. By plugging fractures that occur in wellbore cement, reducing permeability of fractures, both environmental safety and economics of subsurface operations will be improved for geothermal energy and oil and gas production.

Self-healing atmospheric plasma sprayed Mn1.0Co1.9Fe0.1O4 protective interconnector coatings for solid oxide fuel cells

Science.gov (United States)

Grünwald, Nikolas; Sebold, Doris; Sohn, Yoo Jung; Menzler, Norbert Heribert; Vaßen, Robert

2017-09-01

Dense coatings on metallic interconnectors are necessary to suppress chromium poisoning of SOFC cathodes. Atmospherically plasma sprayed (APS) Mn1.0Co1.9Fe0.1O4 (MCF) protective layers demonstrated reduced chromium related degradation in laboratory and stack tests. Previous analyses revealed strong microstructural changes comparing the coating's as-sprayed and operated condition. This work concentrates on the layer-densification and crack-healing observed by annealing APS-MCF in air, which simulates the cathode operation conditions. The effect is described by a volume expansion induced by a phase transformation. Reducing conditions during the spray process lead to a deposition of the MCF in a metastable rock salt configuration. Annealing in air activates diffusion processes for a phase transformation to the low temperature stable spinel phase (T coating. The process decelerates when the cracks are closed, as the gas route is blocked and further oxidation continues over solid state diffusion. The self-healing abilities of metastable APS coatings could be interesting for other applications.

Nanocontainer-Enhanced Self-Healing for Corrosion-Resistant Ni Coating on Mg Alloy.

Science.gov (United States)

Xie, Zhi-Hui; Li, Dan; Skeete, Zakiya; Sharma, Anju; Zhong, Chuan-Jian

2017-10-18

The ability to manipulate the functionalization of Ni coating is of great importance in improving the corrosion resistance of magnesium (Mg) alloy for many industrial applications. In the present work, MCM-41 type mesoporous silica nanocontainers (MSNs) loaded with corrosion inhibitor (NaF) were synthesized and employed as smart reinforcements to enhance the integrity and corrosion inhibition of the Ni coating. The incorporation of the F-loaded MSNs (F@MSNs) to enhance the corrosion resistant capacity of a metallic coating is reported for the first time. The mesoporous structures of the as-prepared MSNs and F@MSNs were confirmed by transmission electron microscopy (TEM), small angle X-rays scattering (SAXS), and N 2 adsorption-desorption isotherms. The X-ray photoelectron spectroscopy (XPS) data demonstrated the successful immobilization of fluoride ion on the MSNs and formation of a magnesium fluoride (MgF 2 ) protective film at the corrosion sites of the Mg alloy upon soaking in a F@MSNs-containing NaCl solution. The results from potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) for both bare Mg alloy and Ni coatings with and without F@MSNs have revealed a clear decrease in corrosion rate in a corrosive solution for a long-time immersion due to the introduction of F@MSNs. These findings open new opportunities in the exploration of self-healing metallic coatings for highly enhanced anticorrosion protection of Mg alloy.

Microencapsulation of 2-octylcyanoacrylate tissue adhesive for self-healing acrylic bone cement.

Science.gov (United States)

Brochu, Alice B W; Chyan, William J; Reichert, William M

2012-10-01

Here, we report the first phase of developing self-healing acrylic bone cement: the preparation and characterization of polyurethane (PUR) microcapsules containing a medical cyanoacrylate tissue adhesive. Capsules were prepared by interfacial polymerization of a toluene-2,4-diisocyanate-based polyurethane prepolymer with 1,4-butanediol to encapsulate 2-octylcyanoacrylate (OCA). Various capsule characteristics, including: resultant morphology, average size and size distribution, shell thickness, content and reactivity of encapsulated agent, and shelf life are investigated and their reliance on solvent type and amount, surfactant type and amount, temperature, pH, agitation rate, reaction time, and mode of addition of the oil phase to the aqueous phase are presented. Capsules had average diameters ranging from 74 to 222 μm and average shell thicknesses ranging from 1.5 to 6 μm. The capsule content was determined via thermogravimetric analysis and subsequent analysis of the capsules following up to 8 weeks storage revealed minimal loss of core contents. Mechanical testing of OCA-containing capsules showed individual capsules withstood compressive forces up to a few tenths of Newtons, and the contents released from crushed capsules generated tensile adhesive forces of a few Newtons. Capsules were successfully mixed into the poly(methyl methacrylate) bone cement, surviving the mixing process, exposure to methyl methacrylate monomer, and the resulting exothermic matrix curing. Copyright © 2012 Wiley Periodicals, Inc.

Anyonic self-induced disorder in a stabilizer code: Quasi many-body localization in a translational invariant model

Science.gov (United States)

Yarloo, H.; Langari, A.; Vaezi, A.

2018-02-01

We enquire into the quasi many-body localization in topologically ordered states of matter, revolving around the case of Kitaev toric code on the ladder geometry, where different types of anyonic defects carry different masses induced by environmental errors. Our study verifies that the presence of anyons generates a complex energy landscape solely through braiding statistics, which suffices to suppress the diffusion of defects in such clean, multicomponent anyonic liquid. This nonergodic dynamics suggests a promising scenario for investigation of quasi many-body localization. Computing standard diagnostics evidences that a typical initial inhomogeneity of anyons gives birth to a glassy dynamics with an exponentially diverging time scale of the full relaxation. Our results unveil how self-generated disorder ameliorates the vulnerability of topological order away from equilibrium. This setting provides a new platform which paves the way toward impeding logical errors by self-localization of anyons in a generic, high energy state, originated exclusively in their exotic statistics.

Pastoral care and healing in Africa: Towards an Adamic Christological practical theology imagination for pastoral healing

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Vhumani Magezi

2016-11-01

Full Text Available This article argues that the challenge and need for relevant ministry models is critical for effective Christian ministry and pastoral ministry as practical life ministry. It establishes an Adamic Christological model as a paradigm that provides a practical effective ministerial approach in Africa, particularly within the context of pastoral care and healing. This framework reveals Christ’s complete identification with African Christians in their contextual sufferings as the New Adam without compromising authentic gospel reality. In employing the Adamic Christological framework as the anchor for African pastoral and healing ministry, a model for African Christians’ daily response to their various contextual sufferings is constructed. This responsive model bridges the gap between the ascension of Christ and the interim period of Christianity by instituting God’s ongoing personal presence in believers’ suffering through the Holy Spirit (pneumatology as an encouraging and comforting reality that should enable Christians to cope in their suffering. It is argued that this Adamic Christological framework provides a practical theological model that contributes to healing and hope in pastoral care through practical knowing that impacts and imparts meaning in life.

Custom anatomic healing abutments

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Vinayak S Gowda

2016-01-01

Full Text Available Dental implants with their increasing success rates and predictability of final outcome are fast becoming the treatment of choice for replacing missing teeth. Considering the success of immediate implant placement in reducing tissue loss and achieving good esthetic results, is making it a more popular treatment modality in implant dentistry. Understanding the management of gingival tissues in relation to implants to obtain maximum esthetics is of utmost importance. The use of provisional abutments and immediate temporization has a proven track record of their ability to produce optimal esthetics and to guide the tissue response during the healing phase. With careful patient selection and execution, customized healing abutments can provide an effective method to enhance the esthetic and emergence profile for anterior implant restorations.