3,622 research outputs found
Jasmine Pasha; Shruti Pandey; Chandsi Sharma
No full textWhen the recession hit in 2008, individuals gave up all the hopes and faith in banks and financial institutions. Cryptocurrency system was established in order to remove banks. Satoshi Nakamoto, who might be a person or a community of individuals, created Bitcoin with the goal of allowing individuals to send money to each other without the need of a bank or a related parties. Mainly bitcoin was created to let anyone undertake money transfers without depending on governments or banking firms. The following study majorly highlights the acceptance of crypto – currency in India, especially amongst the younger investors, and whether or not they believe in the future and sustainability of Crypto – currency, especially Bitcoin, given that it is, by far the largest digital coin, in respect with the market capitalization. We took a survey, to understand the investing behaviour of the Indian population. Our study included convenience sampling, in the age group of 20 – 40 years, analysis of which is talked upon in the following section. Knowing that not all favour crypto – currency, due to many reasons, the paper also talks about the issues and challenges that Bitcoin, and other digital coins face in the market, on both, domestic and global level. In the next immediate section, we shall also look at the evolution of Bitcoin, its trade mechanism and the turning point for India, for this new age technology
sj-docx-2-npx-10.1177_1934578X211056753 - Supplemental material for Ayurvedic Medicinal Plants Against COVID-19: An <i>In Silico</i> Analysis
No full textSupplemental material, sj-docx-2-npx-10.1177_1934578X211056753 for Ayurvedic Medicinal Plants Against COVID-19: An In Silico Analysis by Bharat Krushna Khuntia, Vandna Sharma, Sahar Qazi, Soumi Das, Shruti Sharma, Khalid Raza and Gautam Sharma in Natural Product Communications</p
sj-xlsx-1-npx-10.1177_1934578X211056753 - Supplemental material for Ayurvedic Medicinal Plants Against COVID-19: An <i>In Silico</i> Analysis
No full textSupplemental material, sj-xlsx-1-npx-10.1177_1934578X211056753 for Ayurvedic Medicinal Plants Against COVID-19: An In Silico Analysis by Bharat Krushna Khuntia, Vandna Sharma, Sahar Qazi, Soumi Das, Shruti Sharma, Khalid Raza and Gautam Sharma in Natural Product Communications</p
I Was Addicted to Sex With Married Women
No full textAs a young man, Akhil Sharma revelled in the most dangerous of liaisons, having sex with other men's wives – until the thrill began to pall
TDO882529 Supplemetal Material - Supplemental material for Koebner phenomenon induced by Mantoux testing in a case of papulonecrotic tuberculid
No full textSupplemental material, TDO882529 Supplemetal Material for Koebner phenomenon induced by Mantoux testing in a case of papulonecrotic tuberculid by Geetika Chhabra, Prashant Verma and Shruti Sharma in Tropical Doctor</p
Maldives Resorts: Eco-Friendly Vacations
No full textLuxurious, exclusive and remote, the Maldives are the ultimate beach escape. They’re also a case study in the risks of global warming. Writer Akhil Sharma visits the country’s most eco-friendly resorts and discovers a remarkable cuisine worth protecting
Recollections of a Hindu Hedonist
No full textNovelist Akhil Sharma grew up in a teetotaling Indian household. Here, he tells how discovering a passion for great wine helped him create a new identity out of a painful past
Interview with Lakshmi Raj Sharma, Author of The Tailor’s Needle
No full textInterview with Indian writer Lakshmi Raj Sharma, author of 'The Tailor's needle
Ultrasonic Guided Wave and Acoustic Emission Techniques for monitoring corrosion in Reinforced Concrete Structures
No full textCorrosion of reinforcement is one of the principal causes of premature failure of Reinforced Concrete (RC) structures. In India, the annual loss due to corrosion has been estimated about 4% of the country’s gross domestic product (GDP) i.e., about USD 40 billion in a year in both infrastructure and industry segments. Exposure to extreme environments and the continuous ingress of chlorides in concrete from various sources neutralises the protective passive layer of concrete which is alkaline with a pH ranging from 12 to 13. The presence of moisture and oxygen leads to the formation of oxides and the initiation of reinforcement corrosion takes place. Corrosion of reinforcement in concrete affects the durability of the RC structures in two ways: the formation of rust products with larger volume than steel leads to spalling and the cracking of the concrete cover; and the area of cross-section of the steel bars reduces drastically due to dissolution of the steel leading to pit formation and hence, loss in the tensile strength and load carrying capacity of the structure. Therefore, an early prognosis and diagnosis of corrosion-induced damage in RC structures could facilitate the engineers to adopt correct repair measures.
A large variety of non-destructive techniques have been reported by researchers worldwide for detecting corrosion-induced damage in RC structures like visual inspection, electrochemical, Optical methods, PZT and piezo ceramic patches etc. but they suffer from practical applications owing to large civil infrastructure. Recently, the advent of wave propagation technologies for damage detection in RC structures have given a new dimension to damage monitoring capabilities. In this work, an integrated approach using active Ultrasonic Guided Wave (UGW) and passive Acoustic Emission (AE) technique for corrosion monitoring in RC structures has been attempted. Active UGW monitors the deterioration of reinforcing bar while corrosion takes place in RC structure whereas the AE technique listens to the cracks and records the damage in the surrounding concrete.
Initiation of corrosion in RC structures before it can be observed visually is done using the two techniques. For this, AE sensors were mounted on the concrete surface and typical guided wave modes were propagated through the embedded rebar. The NDT results were co-related with the already established electrochemical techniques. Active monitoring using UGW was found to have limited significance for tracking the initiation of corrosion when only the outer surface of the reinforcing bar is affected. Surface modifications on the embedded rebar during the initial stages of corrosion is clearly indicated by the L(0,1) mode. On the other hand, passive monitoring using AE clearly identified the onset and the initiation of corrosion during the early stages. The origin and the location of micro-cracks were well identified with the help of AE event maps.
Further, the techniques were used to investigate the progression of corrosion-induced damage in RC structures. It was found that UGW clearly differentiated the surface corrosion from the pitting corrosion with the help of specific guided wave modes. On the other hand, AE parameters like AE hits and cumulative signal strength (CSS) successfully picked up the regions of initiation of steel depassivation and progression of corrosion in the form of micro- and macro-cracking in the surrounding concrete. From the AE event maps, the entire damage progression from initiation of corrosion damage to damage progression in the later stages could be clearly observed.
Further, the effect of varying rates and different corrosion environments were investigated using the two wave propagation techniques. It was confirmed that corrosion mechanism is unaltered by varying rates of accelerated corrosion though the damage progression is delayed and picked up by both UGW and AE. In case of RC beams subjected to accelerated corrosion in the absence of chlorides simulating slow corrosion, UGW confirmed that pitting is insignificant due to slow steel-concrete bond deterioration, by picking up only delamination. On the other hand, AE clearly indicated the corrosion initiation as well as progression stages by cumulative AE hits.
The efficacy of UGW and AE techniques was also investigated to monitor the corrosion impediment offered using Fiber Reinforced Polymer (FRP) wraps on corroding RC cylinders. UGW monitoring with surface-seeking and core-seeking modes established that pulse-echo method is suitable to assess corrosion delay in FRP wrapped samples. The recorded AE hits exhibited significant decrease after the wrapping was done indicating success in corrosion impediment. This was confirmed by drop in the values of amplitude of AE hits from 100 dB to 65 dB after wrapping. No peak/knee was observed in the CSS curve, indicating that FRP wraps effectively delayed the corrosion progression.
It is observed that corrosion-induced damage in RC structures can effectively be tracked right from initiation to progression to concrete cracking using an integrated health monitoring approach involving wave propagation technologies of active ultrasonic guided wave and passive acoustic emission techniques along with benchmark electrochemical measurements. This would go a long way in non-destructive evaluation of residual capacities of reinforcements, which would help a great deal in devising a post-corrosion maintenance strategy of RC structures
Modified Epoxy Coatings for Corrosion Inhibition in Reinforcing Bars in Concrete
No full textCorrosion of reinforced concrete structures is one of the biggest problems faced by the construction industry with billions of dollars spent annually on corrosion control and mitigation. Epoxy Coated Rebars (ECRs) have been reported to effectively mitigate corrosion in concrete structures. However, their utilization is constrained by the presence of micro-pores and the inherent brittleness of epoxy coatings. This study delves into the mechanisms of corrosion inhibition through the application of nano-modified epoxy-based coatings. Three distinct formulations of modified epoxy-based coatings were precisely evaluated: nano-clay-modified epoxy coatings with polyaniline, graphene-derivatives modified epoxy coatings with carbon nanotubes and self-healing tung-oil microcapsules-based nano-modified epoxy coatings for plain bars directly and when they were further embedded in concrete and exposed to accelerated chloride corrosion. A multifaceted evaluation approach of Non-Destructive Testing (NDT) and Destructive testing techniques were employed to ascertain coating corrosion efficacy comprehensively. NDT monitoring comprises of visual inspection, corrosion current measurements and ultrasonic guided waves monitoring techniques whereas destructive testing techniques involved evaluation of loss in mass, tensile strength and pull-out strength vis-à-vis corrosion exposure.
Nano-clay modified epoxy coatings examines the efficacy of nano-modified epoxy coatings using four different silane-treated nano-clays (Montmorillonite-MMT, Organic Montmorillonite-OMMT (Cloisite®15A and Cloisite®30B) and Halloysite-HNT) in a combination with polyaniline (PANI). PANI being good pigment material for anti-corrosion coatings is expected to provide enhanced corrosion resistance due to its unique ability to intercept electrons from the metal surface and transfer them to outside the coating. It was confirmed that nano-clay modified epoxy coatings showed superior performance in comparison with pure epoxy coatings, as a result of enhanced barrier properties by nano-clay and synergetic effect of polyaniline fragments closely stacked with nano-sized nano-clay platelets throughout the coating. Delay in corrosion initiation in pure epoxy is 7-8 days in comparison to 70-75 days for PANI with Cloisite®30B nano-clay. Further, ultrasonic guided waves transmitted signals dropped to zero for PE samples in 40 days whereas in PANI with Cloisite®30B after 90 days of exposure ultrasonic signals fall by only 10%. Notably, formulations featuring Cloisite®30B nano-clay with PANI showcased superior barrier properties, with the intercalation of nano-clay particles facilitating tortuous diffusion pathways, thereby impeding aggressive ion ingress and corrosion propagation. Additionally, hydroxyl group of Cloisite®30B promotes interfacial interaction between nano-clay and polymer matrix resulting in impermeable network. Characterization results of silane-treated clays demonstrated the successful grafting of the silane agent on the nano-clay structure, while FE-SEM of different coatings displays the dispersion of nano-fillers inside the coating matrix.
Incorporation of graphene-derivatives in the form of graphene oxide (GO) and reduced graphene oxide (rGO) with carbon nanotubes (CNT) and silane agents was studied further for improved ductility and corrosion inhibition properties. Hybrid mixture of CNTs and rGO/GO enhances the mechanical strength of the coating matrix whereas silane agents improve dispersion and bonding characteristics of nano-fillers. The corrosion initiates earlier in rGO/CNT coatings, occurring within 50 days, while no corrosion was observed in GO/CNT coatings even after 150 days of exposure to corrosion. Additionally, in ultrasonic guided wave monitoring, transmitted signals dropped to zero for rGO/CNT samples in 125 days whereas in GO/CNT coatings after 150 days of exposure ultrasonic signals are completely healthy. GO exhibited superior corrosion inhibition performance over rGO, due to its successful blocking of aggressive larger chloride ions, by providing a dense impenetrable network due to the presence of functional groups on basal planes of GO sheets.
Further the nano-clay and graphene derivatives-based coatings were further examined with self-healing tung-oil microcapsules to develop smart self-healing coatings. In smart nano-clay modified epoxy coating studies, Cloisite®15A nano-clay were incorporated with tung-oil microcapsules in epoxy coatings (MNC) and compared with pure epoxy. These coatings were pre-damaged to investigate the self-healing capabilities of coatings. Corrosion initiates in 15–17 days for NC coatings (only nano-clay) and 8–10 days for MC coatings (only tung-oil microencapsulated epoxy coating), whereas it initiates in 30–35 days with MNC coatings. Synergetic effect of nano-filler with self-healing microcapsules enhanced the overall performance of epoxy coatings. Smart graphene-derivatives (GO and rGO) modified epoxy coating was also studied with tung-oil microcapsules (MrGO and MGO). A dual layer coating combination (M+GO) with additional dual coating of MC coating as top layer and GO/CNT coating as base layer was also investigated. All three coatings exhibit encouraging outcomes after 160 days of accelerated corrosion exposure; however, in the case of the M+GO coatings, there is no corrosion initiation at all after 160 days. Smart coatings formulations exhibited pronounced self-healing attributes, facilitated by tung-oil polymerization triggered upon by coating damage or corrosion initiation. By using tung-oil in nano-modified epoxy coatings, significant reductions in mass loss alongside, noteworthy enhancements in residual tensile strength vis-à-vis pure epoxy coatings, with negligible compromise on bond strength was observed.
In essence, this research effort brings out the pivotal role of advanced nano-modified epoxy coatings in mitigating corrosion-induced structural degradation, thereby bolstering infrastructure resilience and longevity. The understanding obtained from this research offers invaluable insights into the development of robust, cost-effective, and environmentally sustainable corrosion mitigation strategies, vital for fostering resilient infrastructure in the face of evolving challenges
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