Investigation on the Autonomic Structural Self-Healing of FRPC using Microencapsulated 5E2N/Grubbs Catalyst System for Low Temperature Applications

ABSTRACT Investigation on the autonomic structural self-healing of FRPC using microencapsulated 5E2N/Grubbs catalyst system for low temperature applications Mohammad Asgar Khan, Ph.D. Concordia University, 2016 Structural self-healing of Fiber Reinforced Polymer Composites (FRPC) using microencapsulated 5E2N/Grubbs catalyst system is investigated in this work for low temperature applications. Microcapsule containing liquid 5E2N monomer in poly melamine urea formaldehyde (PMUF) shells have been synthesized following the in-situ polymerization technique. The effects of stirring speed and concentration of surfactant on the quality of microcapsules in terms of their average sizes, size distribution, surface morphology and shell thickness are investigated. An optimum combination of stirring speed-SLS concentration is established through numerous synthesis trials of microcapsules. The feasibility of self-healing with the current materials system is first demonstrated by visually observing the healing of crack network that is created on unreinforced epoxy samples impacted with high velocity projectiles. Different strength-based approaches like impact-heal-flexure, flexure-heal-flexure are examined to evaluate the self-healing performance of FRPC in the preliminary investigations. A fracture based approach based on the mode II delamination of FRPC which deals with determining material properties independent of geometry of samples is found to be a better choice for the evaluation of healing performance of FRPC. In the new proposed protocol, healing performance is evaluated by measuring and comparing the mode II fracture toughness of regular neat (not incorporated with healing agents) and modified (incorporated with healing agents) FRPC samples during the Non pre-cracked (NPC) and Pre-cracked (PC) test post healing without any manual intervention for achieving healing. Healing performance index, instead of healing efficiency, is defined by comparing the fracture toughness of regular and modified samples taking into account the possible toughening or weakening effect of incorporating healing agents into the composites. Healing performance index is shown to be a better and realistic indicator of actual healing performance than conventional healing efficiency definition. Effects of average size and concentration of microcapsules on the self-healing performance of FRP composites are investigated at room temperature using the proposed protocol. Finally, the effect of low temperature on self-healing performance of FRP composites is evaluated

Citric Acid-catalyzed Solvent Free, an Efficient One-pot Synthesis of 2, 3-Dihydro-1H-1, 5-Benzodiazepine Derivatives

2,3-Dihydro-1H-1,5-benzodiazepines are synthesized by reaction of o-Phenylenediamine with ketones (acyclic / cyclic) under solvent free conditions in the presence of citric acid in short reaction time with excellent yield

Thermodynamic modeling of the Mg-Mn-(Al, Zn) systems

A self-consistent thermodynamic model of the Mg-Mn, Al-Mn, Mn-Zn binary systems as well as the Mg-Al-Mn and Mg-Mn-Zn ternary systems has been developed. The major difference between this work and the already existing assessments of these systems is the application of the modified quasichemical model for the liquid phase in each system while most of the existing descriptions use the random mixing model. Further, this model is also used to describe one intermediate solid solution phase in the Mn-Zn system. In the absence of key experimental data for the Mg-Mn system, the calculated thermodynamic quantities from the model have been found comparable with other similar systems. The critical temperature of the Mg-Mn liquid miscibility gap has been estimated with the available empirical equation and found to be in acceptable agreement with the calculated value. A comparison between the current work and the most recent work on the Al-Mn system that uses the same model for the liquid phase reveals that better agreement with the experimental data with less number of model parameters has been achieved in the current work. The Mn-Zn system has been modeled for the entire compositon range and wide temperature range starting from room temperature. The accepted experimental data are well reproduced with the current description of the Mn-Zn system. Kohler symmetric extrapolation model has been used to calculate both Mg-Al-Mn and Mg-Mn-Zn systems. The thermodynamic description of the Mg-Al-Mn system has been verified by extensive comparison with the available experimental data from numerous independent experiments. However, the calculated Mg-Mn-Zn system could not be thoroughly verified due to the lack of experimental data. The model can satisfactorily reproduce all the invariant points and the key phase diagram and thermodynamic features of the Mg-Al-Mn, Mg-Mn-Zn ternary systems and the binary sub-systems

Relationship of Physical Properties of Limestone and Marble with Rock Strength Under Specific Geological Conditions from Khyber Region Hunza

The uniaxial compressive strength (UCS) is one of the input parameters mostly used in surface andunderground designs. A literature review revealed that most of the empirical equations between UCS and Schmidthammer rebound number (N) are not satisfactory because of the low coefficient of correlation. In most of the cases, asingle formula is used for all types of rocks. In this study, a relationship UCS with N, slake durability, moisture content,and specific gravity has been developed for a particular limestone and marble deposit. These equations help todetermine the strength of these deposits directly using N value and other properties. The UCS value increased withincreasing N value, specific gravity, and slake durability. While the UCS value decreased with increasing moisturecontent. A relation between slaking cycles and slake durability index is also developed. In this study, the slakedurability value decreased with increasing slaking cycles for both limestone and marble. The UCS showed a linearrelationship with these physical properties

Apparel 4.0: A Review of the Apparel Industry’s Adoption of Frontier Technologies

The Textile & Apparel (T&A) industry has been recognized for its modest shifts. This review paper, however, has examined the state of the apparel industry’s technology adoption, with special reference to 4IR technologies and fast-evolving market preferences in the post-pandemic era. Based on an extensive literature survey, the study concludes that the fourth industrial revolution (4IR) technologies have started gaining ground and disrupting the global apparel value chain. Likewise, Covid-19 too has brought considerable disruptions, driving organizational changes faster than ever. On one hand, Covid-19 has caused a significant adverse impact on the apparel industry, impacting brands, producers, and workers across the world. On the other hand, it has accelerated the adoption of frontier technologies by the industry. The Fourth Industrial Revolution (4IR) is transforming the apparel sector in design, development, production, supply chain, and marketing value segments. Besides process automation, frontier 4IR technologies such as 3D knitting and printing, robotics and intelligent manufacturing, virtual and augmented reality, artificial intelligence, business analytics, IoT, etc., have started shaping the future of the T&A industry. The paper should be of interest to both market actors (e.g., producers and marketers) and market facilitators (e.g., policymakers and academia). Keywords:Textile & Apparel (T&A) industry, Fourth Industrial Revolution (4IR), COVID-19, frontier technologies, fashion cycle, automation, biotechnology, apparel 4.0 DOI: 10.7176/EJBM/14-22-04 Publication date: November 30th 2022

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

An Efficient One-Pot Synthesis of 1, 5-Benzodiazepine Derivatives Catalyzed by TBAB under Mild Conditions

2,3-Dihydro-1H-1,5-benzodiazepines were synthesized by reaction of o-phenylenediamine with ketones (acyclic / cyclic) under solvent free conditions in the presence of tetra butyl ammonium bromide (TBAB) in short reaction time with excellent yield

Ecological restoration of habitats invaded by Leucanthemum vulgare that alters key ecosystem functions.

Precise assessment of the impacts of invasive alien species (IAS) on ecosystem structure and functions is paramount for implementing appropriate management and restoration strategies. Here we investigated the impacts of Leucanthemum vulgare (ox-eye daisy), an aggressive invader in Kashmir Himalaya, on species diversity and primary productivity. We also evaluated bunch of strategies for the ecological restoration of the habitats invaded by this species. We found that uninvaded plots harbored on an average of 6.11 (±2.92) more species per 1m2 of quadrat than invaded plots. At multivariate scale, the ordination (nMDS) and ANOSIM exhibited significant differences between invaded and uninvaded plots with R = 0.7889 and p < 0.001. The decrease in diversity indices in invaded as compared to uninvaded plots was associated with more productive plant communities due to Leucanthemum invasion. Higher altitude Gulmarg site was more affected by Leucanthemum invasion than lower altitude Drung site. We tested different approaches for restoration and management of invaded habitats that include herbicide treatment at seedling stage, herbicide treatment before and after flowering stage, mowing and herbicide treatment together, joint mowing, digging and herbicide treatment and Leucanthemum uprooting. Among these treatments, uprooting and combined digging, mowing and herbicide treatment proved to be most effective in controlling Leucanthemum invasion. The implications of these results for effective management of ecologically sensitive and socio-culturally important landscapes are discussed

NGO INTERACTIONS WITH THE PUBLIC SECTOR: The Experience of Proshika's Livestock and Social Forestry Programme

This case study compares Proshika's different experiences of interaction with government in two of its programmes -- Livestock and Social Forestry -- and then draws some general conclusions about the problems and potential for NGO-government relations in Bangladesh. Proshika works with over 14,000 organised groups of landless men and women and provides a 'package' of inputs and services to support both income generation activities and `conscientisation'. The Livestock Programme has provided the government with a well-networked distribution .system for its scarce inputs. This collaboration has served the interests of both government and NGO, allowing the government to distribute vaccines and services more widely, and strengthening Proshika's group-based activities by giving members proper access to inputs and support facilities through which they can generate income from livestock rearing. Most of the group members directly concerned with cattle rasing are rural women. The Social Forestry Programme has been a different experience. It has grown out of Proshika's long involvement in environmental projects, such as its tree plantation campaign, which began in 1976. It has several different areas of activity, such as tree plantation, agroforestry and roadside forestry. The aim of the Programme is for organised group members to gain access to available local public and state-owned resources, such as roadsides, ponds and state reserved forests. The struggle to gain secure access to the `sal' forests, which are managed by the Forest Department, has been a case of negotiation and confrontation by the group members. This contrasts with the livestock case. On the one hand, there has evolved a clash of interests between the group members and the local level Forest Department officials vis-à-vis their allies in the rural power structure. On the other hand, the group has entered into a new form of negotiation over the newly grown forest resources with members of the community in securing a more equitable distribution of intermediate benefits. The conflict of interests between the group members, the rural elites and the Forest Department can only be resolved on the part of the State. Similar experiences have been encountered in the Roadside Forestry Projects. As long. as the Social Forestry Programme involves the extension of services to the rural poor (eg. tree planting and training), the partnership between Proshika and the government runs relatively smoothly. However, Proshika's experience of working at the grassroots indicates that appropriate tenurial arrangements are an essential prequisite to a successful Social Forestry Programme. This paper argues therefore that while mutually beneficial links are possible between GOs and NGOs over input delivery, a restructuring of existing access relationships for poor people to Common Property Resources (CPRs) requires more challenging initiatives by government agencies