Yue Ding, S. Chow, Jinying Chen, A. L. Le Brun, Chun-Ming Wu, A. Duff, Yajun Wang, Vickie HY Wong, Da Zhao, Tzong-Hsien Lee, C. Conn, Hsien‐Yi Hsu, B. Bui, Guei-Sheung Liu, Hsin-Hui Shen
Glaucoma, a major cause of irreversible blindness worldwide, is associated with elevated intraocular pressure (IOP) and progressive loss of retinal ganglion cells (RGCs) that undergo apoptosis. A mechanism for RGCs injury involves impairment of neurotrophic support and exogenous supply of neurotrophic factors has been shown to be beneficial. However, neurotrophic factors can have widespread effects on neuronal tissues, thus targeting neurotrophic support to injured neurons may be a better neuroprotective strategy. In this study, we have encapsulated LM22A-4, a small neurotrophic factor mimetic, into Annexin V-conjugated cubosomes (L4-ACs) for targeted delivery to injured RGCs in a model of glaucoma, which is induced by acute IOP elevation. We have tested cubosomes formulations that encapsulate from 9% to 33% LM22A-4. Our data indicated that cubosomes encapsulating 9% and 17% LM22A-4 exhibited a mixture of Pn3m/Im3m cubic phase, whereas 23% and 33% showed a pure Im3m cubic phase. We found that 17% L4-ACs with Pn3m/Im3m symmetries showed better in-situ and in-vitro lipid membrane interactions than the 23% and 33% L4-ACs with Im3m symmetry. In vivo experiments showed that 17% L4-ACs targeted the posterior retina and the optic nerve head, which prevented RGCs loss in a mouse model of acute IOP elevation. These results provide evidence that cubosomes-based LM22A-4 delivery may be a useful targeted approached to prevent the progression of RGCs loss in glaucoma.
{"title":"Targeted Delivery of LM22A-4 by Cubosomes Protects Retinal Ganglion Cells in an Experimental Glaucoma Model","authors":"Yue Ding, S. Chow, Jinying Chen, A. L. Le Brun, Chun-Ming Wu, A. Duff, Yajun Wang, Vickie HY Wong, Da Zhao, Tzong-Hsien Lee, C. Conn, Hsien‐Yi Hsu, B. Bui, Guei-Sheung Liu, Hsin-Hui Shen","doi":"10.2139/ssrn.3718055","DOIUrl":"https://doi.org/10.2139/ssrn.3718055","url":null,"abstract":"Glaucoma, a major cause of irreversible blindness worldwide, is associated with elevated intraocular pressure (IOP) and progressive loss of retinal ganglion cells (RGCs) that undergo apoptosis. A mechanism for RGCs injury involves impairment of neurotrophic support and exogenous supply of neurotrophic factors has been shown to be beneficial. However, neurotrophic factors can have widespread effects on neuronal tissues, thus targeting neurotrophic support to injured neurons may be a better neuroprotective strategy. In this study, we have encapsulated LM22A-4, a small neurotrophic factor mimetic, into Annexin V-conjugated cubosomes (L4-ACs) for targeted delivery to injured RGCs in a model of glaucoma, which is induced by acute IOP elevation. We have tested cubosomes formulations that encapsulate from 9% to 33% LM22A-4. Our data indicated that cubosomes encapsulating 9% and 17% LM22A-4 exhibited a mixture of Pn3m/Im3m cubic phase, whereas 23% and 33% showed a pure Im3m cubic phase. We found that 17% L4-ACs with Pn3m/Im3m symmetries showed better in-situ and in-vitro lipid membrane interactions than the 23% and 33% L4-ACs with Im3m symmetry. In vivo experiments showed that 17% L4-ACs targeted the posterior retina and the optic nerve head, which prevented RGCs loss in a mouse model of acute IOP elevation. These results provide evidence that cubosomes-based LM22A-4 delivery may be a useful targeted approached to prevent the progression of RGCs loss in glaucoma.","PeriodicalId":18268,"journal":{"name":"Materials Engineering eJournal","volume":"5 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91506809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is a need of time to synthesize and verify the natural biopolymers to reduce the threats to health and environment. The superabsorbent polymers are hydrophilic structure which makes them capable of holding large amount of water in their three dimensional networks. Polysaccharides are highly abundant biopolymers with a variation of structure and properties. They are non-toxic, biocompatible and biodegradable so potentially substitutes the synthetic polymers. Due to their attractive properties, they are used as a rheological modifier in food, pharmaceutical, paper, textile, oil, drilling and score of other industrial and agriculture sectors. This review sheds light on different technologies adopted for SAP materials production based on polysaccharide as green biosources and their applications. The methods used for quantifying the SAP practical features are discussed as well.
{"title":"Polysaccharide Based Superabsorbent Polymer : A Review","authors":"M. Khan, Wasim A. Qadri, S. Loonker","doi":"10.2139/ssrn.3904461","DOIUrl":"https://doi.org/10.2139/ssrn.3904461","url":null,"abstract":"It is a need of time to synthesize and verify the natural biopolymers to reduce the threats to health and environment. The superabsorbent polymers are hydrophilic structure which makes them capable of holding large amount of water in their three dimensional networks. Polysaccharides are highly abundant biopolymers with a variation of structure and properties. They are non-toxic, biocompatible and biodegradable so potentially substitutes the synthetic polymers. Due to their attractive properties, they are used as a rheological modifier in food, pharmaceutical, paper, textile, oil, drilling and score of other industrial and agriculture sectors. This review sheds light on different technologies adopted for SAP materials production based on polysaccharide as green biosources and their applications. The methods used for quantifying the SAP practical features are discussed as well.","PeriodicalId":18268,"journal":{"name":"Materials Engineering eJournal","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73140532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wear and its interrelated noise are inevitable occurrences when two materials are in contact with each other. The correlation of the two parameters leads to acoustic study for health monitoring of machines and components. Various empirical models have been proposed using ball-on-disc tribometer using a conventional one ball contact with the disc. In our investigation we used a two-point contact over a rotating disc. To imitate a machine environment where one component is in multiple contact at any instance, a ball holder is designed, which can be affixed on to a conventional tribometer and can engage two balls at the same time sliding over a disc specimen. For the noise parameter, non-contact technique is adapted instead of an acoustic analyzer where a microphone is placed at a fixed distance and in close vicinity to the noise source. The material of the balls was selected to be stainless steel while the material of the disc is mild steel. The balls slide over the disc for a fixed duration at a constant low speed rpm until the wear depth is significant for analysis. In-situ analysis of wear parameters including surface roughness, wear depth and wear profile of the disc was measured systematically. The results from the tribometer are in the form of penetration depth, while the sound signal obtained from microphone is filtered using microphone software and plotted as sound pressure (in dB). The results show a good correlation of wear to the frictional noise at both the contacts and helped us in our subsequent study of modelling wear dependencies. Comparison of wear parameters to noise parameters concludes that the frictional noise is directly related to wear generation at contact.
{"title":"Empirical Modelling of Frictional Noise and Two-Point Contact Using Ball-On-Disc Tribometer","authors":"K. Basit, H. Shams, M. Khan, A. Mansoor","doi":"10.2139/ssrn.3717985","DOIUrl":"https://doi.org/10.2139/ssrn.3717985","url":null,"abstract":"Wear and its interrelated noise are inevitable occurrences when two materials are in contact with each other. The correlation of the two parameters leads to acoustic study for health monitoring of machines and components. Various empirical models have been proposed using ball-on-disc tribometer using a conventional one ball contact with the disc. \u0000 \u0000In our investigation we used a two-point contact over a rotating disc. To imitate a machine environment where one component is in multiple contact at any instance, a ball holder is designed, which can be affixed on to a conventional tribometer and can engage two balls at the same time sliding over a disc specimen. For the noise parameter, non-contact technique is adapted instead of an acoustic analyzer where a microphone is placed at a fixed distance and in close vicinity to the noise source. The material of the balls was selected to be stainless steel while the material of the disc is mild steel. The balls slide over the disc for a fixed duration at a constant low speed rpm until the wear depth is significant for analysis. In-situ analysis of wear parameters including surface roughness, wear depth and wear profile of the disc was measured systematically. \u0000 \u0000The results from the tribometer are in the form of penetration depth, while the sound signal obtained from microphone is filtered using microphone software and plotted as sound pressure (in dB). The results show a good correlation of wear to the frictional noise at both the contacts and helped us in our subsequent study of modelling wear dependencies. Comparison of wear parameters to noise parameters concludes that the frictional noise is directly related to wear generation at contact.","PeriodicalId":18268,"journal":{"name":"Materials Engineering eJournal","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85630377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Industrial Internet of Things (IIoT) is still a new research area. The main emphasis of the IIoT literature is on identifying the challenges involved in implementation of the IIoT. This paper summarizes the literature on the barriers faced by any stakeholder aiming to adopt IIoT anywhere. After reviewing 31 empirical studies, three domains of factors have been identified, individual (skills, abilities and knowledge), institutional (organizational/management-related), and structural (technical and economic infrastructures). A total of eleven factors across the three dimensions have been extracted. The most important factors were the absence of human capital (limited individual soft and technical knowledge, skills and abilities), low information security experience leading to a high probability data leaks and high management resistance from employees and leaders. To strengthen information for successful IIoT implementation, this paper proposes the mandate of Security, Education, Training, and Awareness (SETA) initiatives for any stakeholder interested in IIoT adoption. A Causal loop diagram for the IIoT implementation is also developed and discussed in this work.
{"title":"A Multi-Level Analysis of the Implementation of Industrial Internet of Things: Challenges and Future Prospects","authors":"S. Rajab, P. Saxena, K. Salonitis","doi":"10.2139/ssrn.3718005","DOIUrl":"https://doi.org/10.2139/ssrn.3718005","url":null,"abstract":"Industrial Internet of Things (IIoT) is still a new research area. The main emphasis of the IIoT literature is on identifying the challenges involved in implementation of the IIoT. This paper summarizes the literature on the barriers faced by any stakeholder aiming to adopt IIoT anywhere. After reviewing 31 empirical studies, three domains of factors have been identified, individual (skills, abilities and knowledge), institutional (organizational/management-related), and structural (technical and economic infrastructures). A total of eleven factors across the three dimensions have been extracted. The most important factors were the absence of human capital (limited individual soft and technical knowledge, skills and abilities), low information security experience leading to a high probability data leaks and high management resistance from employees and leaders. To strengthen information for successful IIoT implementation, this paper proposes the mandate of Security, Education, Training, and Awareness (SETA) initiatives for any stakeholder interested in IIoT adoption. A Causal loop diagram for the IIoT implementation is also developed and discussed in this work.","PeriodicalId":18268,"journal":{"name":"Materials Engineering eJournal","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88577187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-23DOI: 10.15587/1729-4061.2020.214308
V. Subbotina, Oleg Sоbоl`, V. Belozerov, V. Shnayder, O. Smyrnov
It was determined that in an electrolyte containing 1.75 g/L KOH+1 g/L Na 2 SiO 3 +2 g/L NaAlO 2 , with an increase in current density from 15 A/dm 2 to 50 A/dm 2 , the phase composition of the coating changes. In the three-phase state (aluminum titanate, rutile, and amorphous-like phase), with increasing j, instead of an amorphous-like phase, a crystalline mullite phase appears. The hardness of the coating increases from 5400 MPa to 12500 MPa. It was found that, in combination with aluminum titanate, mullite is the basis for achieving high hardness in the coating. The formation of a ceramic micro-arc oxide coating on the surface of the VT3-1 titanium alloy makes it possible to reduce the dry friction coefficient by more than 5 times to f=0.09. The effect of electrolysis conditions during micro-arc oxidation of the VT3-1 alloy (titanium-based) on the growth kinetics, surface morphology, phase-structural state, and physical and mechanical characteristics (hardness, coefficient of friction) of oxide coatings was studied. It was found that the process in the mode of micro-arc discharges is stably implemented on the VT3-1 alloy in an alkaline (KOH) electrolyte with additions of sodium aluminate (NaAlO 2 ) and liquid glass (Na 2 SiO 3 ). This makes it possible to obtain coatings up to 250 μm thick. In this case, a linear dependence of the coating thickness on the time of the MAO process is observed. The growth rate of the coating increases with increasing current density. The highest growth rate was 1.13 μm/min. It was revealed that in an electrolyte containing 1 g/L KOH+14 g/L NaAlO 2 with an increase in the duration of oxidation from 60 to 180 minutes, the relative content of the high-temperature phase, rutile, increases. In the coatings obtained in the electrolyte 1.75 g/L KOH+1 g/L Na 2 SiO 3 +2 g/L NaAlO 2 , with an increase in the duration of the MAO process, the relative content of the amorphous-like phase decreases and the content of the crystalline phase of mullite (3Al 2 O 3 ·2SiO 2 ) increases
{"title":"An Experimental Analysis of the Influence of Electrolyte Compositions, Current Density and Duration of the Microarc Oxidation Process on the Structural Phase State and Properties of VT31 Titanium Alloy","authors":"V. Subbotina, Oleg Sоbоl`, V. Belozerov, V. Shnayder, O. Smyrnov","doi":"10.15587/1729-4061.2020.214308","DOIUrl":"https://doi.org/10.15587/1729-4061.2020.214308","url":null,"abstract":"It was determined that in an electrolyte containing 1.75 g/L KOH+1 g/L Na 2 SiO 3 +2 g/L NaAlO 2 , with an increase in current density from 15 A/dm 2 to 50 A/dm 2 , the phase composition of the coating changes. In the three-phase state (aluminum titanate, rutile, and amorphous-like phase), with increasing j, instead of an amorphous-like phase, a crystalline mullite phase appears. The hardness of the coating increases from 5400 MPa to 12500 MPa. It was found that, in combination with aluminum titanate, mullite is the basis for achieving high hardness in the coating. The formation of a ceramic micro-arc oxide coating on the surface of the VT3-1 titanium alloy makes it possible to reduce the dry friction coefficient by more than 5 times to f=0.09. The effect of electrolysis conditions during micro-arc oxidation of the VT3-1 alloy (titanium-based) on the growth kinetics, surface morphology, phase-structural state, and physical and mechanical characteristics (hardness, coefficient of friction) of oxide coatings was studied. It was found that the process in the mode of micro-arc discharges is stably implemented on the VT3-1 alloy in an alkaline (KOH) electrolyte with additions of sodium aluminate (NaAlO 2 ) and liquid glass (Na 2 SiO 3 ). This makes it possible to obtain coatings up to 250 μm thick. In this case, a linear dependence of the coating thickness on the time of the MAO process is observed. The growth rate of the coating increases with increasing current density. The highest growth rate was 1.13 μm/min. It was revealed that in an electrolyte containing 1 g/L KOH+14 g/L NaAlO 2 with an increase in the duration of oxidation from 60 to 180 minutes, the relative content of the high-temperature phase, rutile, increases. In the coatings obtained in the electrolyte 1.75 g/L KOH+1 g/L Na 2 SiO 3 +2 g/L NaAlO 2 , with an increase in the duration of the MAO process, the relative content of the amorphous-like phase decreases and the content of the crystalline phase of mullite (3Al 2 O 3 ·2SiO 2 ) increases","PeriodicalId":18268,"journal":{"name":"Materials Engineering eJournal","volume":"88 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73625365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Janardhan Padiyara, Reza Mohammadkhania, L. Zanotti Fragonara, I. Petrunin, J. Raposo, A. Tsourdos, Iain Gray
Aircraft maintenance represents 10-20% of the overall operating cost, and heavy C-check and D-check maintenance demands NDT inspection of 100% skin area of composite material fuselages. Delamination and low velocity Barely Visible Impact Damages (BVID) are typical in-service damages found in skin causing small to large sub-surface damages with little or no surface indication. These damages are difficult to detect during manual visual inspection. Conventional manual ultrasonic and advanced Phased Array (PA) scanning of skin followed by data interpretation and analysis for damage sizing is time consuming and cost-inefficient for on-site application; hence a potential task to be automated or robotized. Automated PA inspection by magnetic-adhesion based manipulators, crawlers and scanners have led to rapid inspection rates and lowering the cost of inspection in oil and gas sectors. The composite skin surfaces are painted, smooth and non-magnetic, which invalidates the use of current magnetic adhesion based crawlers for inspection. Despite some previous efforts, the development of automated PA inspection of skin surfaces using a mobile robot is still an unsolved problem. This work is a part of ongoing EU-H2020 project ‘CompInnova’ which aims to develop an integrated NDT approach using combined PA and Infrared Thermography inspection of the fuselage-skin through separate inspection modules mounted on a mobile robot, that will lead to cost-effective combination for on-site automated inspection. A novel vortex based wheeled mobile robot was developed for traversing over the fuselage using adhesion forces generated by means of Electric Ducted Fan (EDF) motors [4]. This robot was designed to carry a PA NDT module [4], but with restrictions on payload (1 Kg.) and minimum water couplant usage requirements. Thus this work presents the development challenges of the PA module for automated PA inspection and to meet the requirements for its integration with robot. PA inspection results obtained by robotic scanning of laminates with impact damages, are evaluated for assessing the functionality and performance of the PA module.
{"title":"Challenges for On-Site Automated Ultrasonic Phased Array Inspection of Composite Aircraft","authors":"M. Janardhan Padiyara, Reza Mohammadkhania, L. Zanotti Fragonara, I. Petrunin, J. Raposo, A. Tsourdos, Iain Gray","doi":"10.2139/ssrn.3718011","DOIUrl":"https://doi.org/10.2139/ssrn.3718011","url":null,"abstract":"Aircraft maintenance represents 10-20% of the overall operating cost, and heavy C-check and D-check maintenance demands NDT inspection of 100% skin area of composite material fuselages. Delamination and low velocity Barely Visible Impact Damages (BVID) are typical in-service damages found in skin causing small to large sub-surface damages with little or no surface indication. These damages are difficult to detect during manual visual inspection. Conventional manual ultrasonic and advanced Phased Array (PA) scanning of skin followed by data interpretation and analysis for damage sizing is time consuming and cost-inefficient for on-site application; hence a potential task to be automated or robotized. Automated PA inspection by magnetic-adhesion based manipulators, crawlers and scanners have led to rapid inspection rates and lowering the cost of inspection in oil and gas sectors. The composite skin surfaces are painted, smooth and non-magnetic, which invalidates the use of current magnetic adhesion based crawlers for inspection. Despite some previous efforts, the development of automated PA inspection of skin surfaces using a mobile robot is still an unsolved problem. \u0000 \u0000This work is a part of ongoing EU-H2020 project ‘CompInnova’ which aims to develop an integrated NDT approach using combined PA and Infrared Thermography inspection of the fuselage-skin through separate inspection modules mounted on a mobile robot, that will lead to cost-effective combination for on-site automated inspection. A novel vortex based wheeled mobile robot was developed for traversing over the fuselage using adhesion forces generated by means of Electric Ducted Fan (EDF) motors [4]. This robot was designed to carry a PA NDT module [4], but with restrictions on payload (1 Kg.) and minimum water couplant usage requirements. Thus this work presents the development challenges of the PA module for automated PA inspection and to meet the requirements for its integration with robot. PA inspection results obtained by robotic scanning of laminates with impact damages, are evaluated for assessing the functionality and performance of the PA module.","PeriodicalId":18268,"journal":{"name":"Materials Engineering eJournal","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90923012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Robotic Mobility in dynamic environments has gained popularity among many researchers over past few years. The environment where human beings perform their normal operations includes narrow spaces, sharp turns, slopes and steps. In addition, some times the field of operation may be found to be chemically hazardous, radioactive or reconnaissance in nature. It is not quite easy to develop intelligent robots with very precise mechanism suitable for specific navigational purposes. The balancing on two wheels and spin on the spot ability with smaller footprints of the bi-differential wheeled mobile robots distinguish them from other multi-wheel counterparts. In this paper some of the basic literatures regarding the motion planning of mobile robots are discussed using different artificial intelligence techniques. The robots can able to reach a respective goal positions by successfully avoiding the intermediate collisions among themselves and with the obstacles using these techniques as control scheme.
{"title":"A Comprehensive Review on Motion Planning of Bi-differential Wheeled Robots in Cluttered Environment Using Various Artificial Intelligent Techniques","authors":"Animesh Chhotray, D. Parhi, P. Kumar, P. Behera","doi":"10.2139/ssrn.3714168","DOIUrl":"https://doi.org/10.2139/ssrn.3714168","url":null,"abstract":"Robotic Mobility in dynamic environments has gained popularity among many researchers over past few years. The environment where human beings perform their normal operations includes narrow spaces, sharp turns, slopes and steps. In addition, some times the field of operation may be found to be chemically hazardous, radioactive or reconnaissance in nature. It is not quite easy to develop intelligent robots with very precise mechanism suitable for specific navigational purposes. The balancing on two wheels and spin on the spot ability with smaller footprints of the bi-differential wheeled mobile robots distinguish them from other multi-wheel counterparts. In this paper some of the basic literatures regarding the motion planning of mobile robots are discussed using different artificial intelligence techniques. The robots can able to reach a respective goal positions by successfully avoiding the intermediate collisions among themselves and with the obstacles using these techniques as control scheme.","PeriodicalId":18268,"journal":{"name":"Materials Engineering eJournal","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84375439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Debora Lima Molter, M. L. Castro, D. D. dos Santos
This paper outlines experimental procedures and numerical analyses to research Hydrogen embrittlement (HE) of the supermatensitic stainless steel (SMSS) S13Cr submitted to different cathodic potentials. Hydrogen diffusion behavior was investigated by means of two electrochemical permeation techniques, namely the double potentiostatic method (DPM) and the step method (SM), and it was also performed thermal desorption spectroscopy (TDS) tests. Apparent Hydrogen diffusion coefficients vary from 1.4 x 10-13 m²/s to 4.7 x 10-12 m²/s and TDS reveals the existence of deep traps, such as interfaces of precipitates and between retained austenite and ferritic matrix. HE effects in terms of reduction of ductility were analyzed through tensile tests and fractographic analysis, where a maximum reduction of elongation of around 14% was measured and a majority of brittle fracture along entire net section was observed in test samples pre charged under -1.5 V/SCE and -1.7 V/SCE. A calculation procedure based on computational simulation via finite element method has been performed, in order to predict mentioned loss of ductility using the experimental data mentioned before. The computational model used a fracture-controlled method under static structural condition, which links reduction of elongation of tensile specimens to the decreasing of critical fracture energies, which, in turn, were achieved through a new mean field approach regarding thermodynamic excess variables. Herein presented observations make it possible to suggest, that S13Cr has good resistance to HE and that the mentioned calculation procedure is reliable, since slight deviations in the magnitude of 5% were observed.
{"title":"The Role of Hydrogen on the Separation of Interfaces of Supermartensitic Stainless Steel S13Cr","authors":"Debora Lima Molter, M. L. Castro, D. D. dos Santos","doi":"10.2139/ssrn.3708758","DOIUrl":"https://doi.org/10.2139/ssrn.3708758","url":null,"abstract":"This paper outlines experimental procedures and numerical analyses to research Hydrogen embrittlement (HE) of the supermatensitic stainless steel (SMSS) S13Cr submitted to different cathodic potentials. Hydrogen diffusion behavior was investigated by means of two electrochemical permeation techniques, namely the double potentiostatic method (DPM) and the step method (SM), and it was also performed thermal desorption spectroscopy (TDS) tests. Apparent Hydrogen diffusion coefficients vary from 1.4 x 10-13 m²/s to 4.7 x 10-12 m²/s and TDS reveals the existence of deep traps, such as interfaces of precipitates and between retained austenite and ferritic matrix. HE effects in terms of reduction of ductility were analyzed through tensile tests and fractographic analysis, where a maximum reduction of elongation of around 14% was measured and a majority of brittle fracture along entire net section was observed in test samples pre charged under -1.5 V/SCE and -1.7 V/SCE. A calculation procedure based on computational simulation via finite element method has been performed, in order to predict mentioned loss of ductility using the experimental data mentioned before. The computational model used a fracture-controlled method under static structural condition, which links reduction of elongation of tensile specimens to the decreasing of critical fracture energies, which, in turn, were achieved through a new mean field approach regarding thermodynamic excess variables. Herein presented observations make it possible to suggest, that S13Cr has good resistance to HE and that the mentioned calculation procedure is reliable, since slight deviations in the magnitude of 5% were observed.","PeriodicalId":18268,"journal":{"name":"Materials Engineering eJournal","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78935632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
JG Mattei, M. Sall, F. Moisy, A. Ribet, E. Balanzat, C. Grygiel, I. Monnet
Gallium nitride was irradiated with fullerene projectiles having an electronic stoppingpower above the threshold needed to promote ion track formation. The structural andchemical changes induced by fullerene irradiation were studied though TransmissionElectron Microscopy (TEM). High resolution TEM inquiries were performed to identifythe structural order along the ion tracks and the strain induced in the latticeneighboring the ion tracks. The TEM investigation pointed out local amorphizationinside the whole tracks and High Resolution TEM studies in the track peripheryevidence local stress in the wurtzite structure. Chemical investigations were carried outby STEM - Electron Energy Loss Spectroscopy (EELS) to describe the chemical orderin the neighboring and inside the ion path. Chemical profiles plotted across ion tracksindicate that the Ga/N stoichiometry is essentially maintained in the core track, anoxidation in the ion track periphery was also detected at the surface. Furthermore, thenitrogen k near-edge fine structure investigation reveals the encapsulation of nitrogenbubbles inside the ion tracks.
{"title":"Fullerene Irradiation Leads to Track Formation Enclosing Nitrogen Bubbles in GaN Material","authors":"JG Mattei, M. Sall, F. Moisy, A. Ribet, E. Balanzat, C. Grygiel, I. Monnet","doi":"10.2139/ssrn.3697738","DOIUrl":"https://doi.org/10.2139/ssrn.3697738","url":null,"abstract":"Gallium nitride was irradiated with fullerene projectiles having an electronic stoppingpower above the threshold needed to promote ion track formation. The structural andchemical changes induced by fullerene irradiation were studied though TransmissionElectron Microscopy (TEM). High resolution TEM inquiries were performed to identifythe structural order along the ion tracks and the strain induced in the latticeneighboring the ion tracks. The TEM investigation pointed out local amorphizationinside the whole tracks and High Resolution TEM studies in the track peripheryevidence local stress in the wurtzite structure. Chemical investigations were carried outby STEM - Electron Energy Loss Spectroscopy (EELS) to describe the chemical orderin the neighboring and inside the ion path. Chemical profiles plotted across ion tracksindicate that the Ga/N stoichiometry is essentially maintained in the core track, anoxidation in the ion track periphery was also detected at the surface. Furthermore, thenitrogen k near-edge fine structure investigation reveals the encapsulation of nitrogenbubbles inside the ion tracks.","PeriodicalId":18268,"journal":{"name":"Materials Engineering eJournal","volume":"83 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81313330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Billington, H. Okazaki, K. Toyoki, Y. Kotani, Y. Takada, Takashi Sato, Y. Kaneko, A. Kato, T. Sasaki, T. Ohkubo, K. Hono, Tetsuya Nakamura
The crystalline phases that comprise the bulk microstructure of an isotropic Ga-containing Nd-Fe-B sintered magnet are identified by in situ elevated-temperature x-ray diffraction for temperatures between 25 and 800°C. Comparing the temperature-dependent volume fractions of the crystalline phases with the coercivity as a function of annealing temperature reveals that the large coercivity enhancements are remarkably well-correlated with the existence of a crystalline Nd6(Fe,Ga)14 phase. Scanning soft x-ray absorption microscopy measurements are used to directly observe the distribution of Fe and Nd in anisotropic as-sintered and optimally-annealed samples and demonstrate that the surface microstructure is similar to bulk. Fe L3-edge x-ray magnetic circular dichroism measurements are used to directly map the demagnetization process in the fractured surfaces of anisotropic as-sintered and optimally-annealed samples. In the as-sintered sample, the demagnetization curves of compositionally different regions all have the the same shape but with a maximum magnetic signal that only depends on the Fe content within the probing depth of the x-ray absorption measurements. In the optimally-annealed sample, the demagnetization curves from compositionally different regions have rather different shapes and the exposed Nd2Fe14B grains without any grain boundary coverage have much lower coercivity than those with. This provides evidence that the grain boundary phase that forms upon annealing is able to protect the Nd2Fe14B grains from magnetization reversal by exchange-decoupling the Nd2Fe14B grains.
{"title":"Relationship between the Microstructure, Local Magnetism and Coercivity in Ga-Containing Nd-Fe-B Sintered Magnets","authors":"D. Billington, H. Okazaki, K. Toyoki, Y. Kotani, Y. Takada, Takashi Sato, Y. Kaneko, A. Kato, T. Sasaki, T. Ohkubo, K. Hono, Tetsuya Nakamura","doi":"10.2139/ssrn.3697716","DOIUrl":"https://doi.org/10.2139/ssrn.3697716","url":null,"abstract":"The crystalline phases that comprise the bulk microstructure of an isotropic Ga-containing Nd-Fe-B sintered magnet are identified by in situ elevated-temperature x-ray diffraction for temperatures between 25 and 800°C. Comparing the temperature-dependent volume fractions of the crystalline phases with the coercivity as a function of annealing temperature reveals that the large coercivity enhancements are remarkably well-correlated with the existence of a crystalline Nd6(Fe,Ga)14 phase. Scanning soft x-ray absorption microscopy measurements are used to directly observe the distribution of Fe and Nd in anisotropic as-sintered and optimally-annealed samples and demonstrate that the surface microstructure is similar to bulk. Fe L3-edge x-ray magnetic circular dichroism measurements are used to directly map the demagnetization process in the fractured surfaces of anisotropic as-sintered and optimally-annealed samples. In the as-sintered sample, the demagnetization curves of compositionally different regions all have the the same shape but with a maximum magnetic signal that only depends on the Fe content within the probing depth of the x-ray absorption measurements. In the optimally-annealed sample, the demagnetization curves from compositionally different regions have rather different shapes and the exposed Nd2Fe14B grains without any grain boundary coverage have much lower coercivity than those with. This provides evidence that the grain boundary phase that forms upon annealing is able to protect the Nd2Fe14B grains from magnetization reversal by exchange-decoupling the Nd2Fe14B grains.","PeriodicalId":18268,"journal":{"name":"Materials Engineering eJournal","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74874167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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