Development of Ferrite-coated Soft Magnetic Composites: Correlation of Microstructure to Magnetic Properties

Soft magnetic composites (SMCs) comprised of ferrite-coated ferrous powder permit isotropic magnetic flux capabilities, lower core losses, and complex designs through the use of traditional powder metallurgy techniques. Current coating materials and methods are vastly limited by the nonmagnetic properties of organic and some inorganic coatings and their inability to withstand high heat treatments for proper stress relief of core powder after compaction. Ferrite-based coatings are ferrimagnetic, highly resistive, and boast high melting temperatures, thus providing adequate electrical barriers between metallic particles. These insulating layers are necessary for reducing eddy current losses by increasing resistivity in order to improve the overall magnetic efficiency and subsequent frequency range. The goals of this work are to correlate ferrite-coated Fe powder composites microstructure for the coating and core powder to magnetic properties such as permeability, coercivity, and core loss. We first explore the relevant concepts of SMC materials from their composition to processing steps to pertinent properties. This thesis employs a suite of characterization techniques for powder and composite properties. We use X-ray diffraction, scanning electron microscopy, and transmission electron microscopy to provide a complete understanding of the effect of processing conditions on ferrite-coated Fe-based SMCs. Magnetic, mechanical, and electrical properties are then analyzed to correlate microstructural features and determine their effect on such properties. In the second part of this thesis, we present a proof of concept study on Al2O3- and Al2O3- Fe3O4-coated Fe powder composites, illustrating magnetization is highly dependent on ferromagnetic volume. We then expand on previous work to compare an ideal, crystalline state using Fe3O4-Fe thin film heterostructures to a highly strained state using bulk powder studies. Fe3O4-coated Fe composites are produced via mechanical milling and analyzed for magnetic core loss dependence on particle size, cure temperature, and microstructure of both coating and core powder. We present a significant increase in core loss related to eddy current loss from coating particles sintering and Fe grain growth. Lastly, a more resistive coating material, NiZnCu-ferrite, is applied for improved resistivity, which leads to lower eddy current loss and improved magnetic performance. By highlighting the importance of microstructure and composition on magnetic properties, a closer look at interfacial features and local microstrain are necessary and accomplished in this work. Future developments of ferrite-based SMC coatings are required to transform the use of electromagnetic devices in today's society.Ph.D., Materials Science and Engineering -- Drexel University, 201

Raw, Unadulterated African Honey for Ulcer Healing in Leprosy:Protocol for the Honey Experiment on Leprosy Ulcer (HELP) Randomized Controlled Trial

Background: Leprosy leads to nerve damage and slow-healing ulcers, which are treatable with routine therapy. There has been a recent resurgence of interest in the use of honey for the treatment of different kinds of wounds. Objective: The aim of this study, Honey Experiment on Leprosy Ulcer (HELP), is to evaluate the healing properties of raw, unadulterated African honey in comparison with normal saline dressing for the treatment leprosy ulcers. Methods: This is a multicenter, comparative, prospective, single-blinded, parallel-group, and 1:1 individually randomized controlled trial to be conducted at The Leprosy Referral Hospital, Chanchaga in Minna, Niger State, North Central Nigeria, and St. Benedict Tuberculosis and Leprosy Rehabilitation Hospital in Ogoja, Cross River State, South-South Nigeria. Raw, unadulterated honey will be used in the ulcer dressing of eligible, consenting participants in the intervention group, whereas those in the control group will be treated by dressing with normal saline. The main outcomes will be the proportion of complete healing and the rate of healing up to 84 days after randomization. Follow-up will be conducted 6 months after randomization. We aim to enroll 90‐130 participants into the study. Blinded observers will examine photographs of ulcers to determine the outcomes. Results: The recruitment of trial participants began on March 14, 2022, and has been continuing for approximately 24 months. Conclusions: Our study will provide an unbiased estimate of the effect of honey on the healing of neuropathic ulcers. Trial Registration: ISRCTN registry ISRCTN10093277; https://www.isrctn.com/ISRCTN1009327

Investigating the sustainability of self-help programmes in the context of leprosy and the work of leprosy missions in Nigeria, Nepal and India : a qualitative study protocol

Leprosy occurs among very poor people who may be stigmatised and pushed further to the margins of society. Programmes to improve social integration and stimulate economic development have been implemented to help break the vicious cycle of poverty, reduced quality of life and ulcer recurrence. These involve forming groups of people, with a common concern, to provide mutual support and form saving syndicates-hence the term 'self-help groups' (SHGs). While there is literature on the existence and effectiveness of SHGs during the funded periods, little is known about their sustainability. We aim to explore the extent to which SHG programme activities have continued beyond the funding period and record evidence of sustained benefits. In India, Nepal and Nigeria, we identified programmes funded by international non-governmental organisations, primarily aimed at people affected by leprosy. In each case, financial and technical support was allocated for a predetermined period (up to 5 years).We will review documents, including project reports and meeting minutes, and conduct semistructured interviews with people involved in delivery of the SHG programme, potential beneficiaries and people in the wider environment who may have been familiar with the programme. These interviews will gauge participant and community perceptions of the programmes and barriers and facilitators to sustainability. Data will be analysed thematically and compared across four study sites. Approval was obtained from the University of Birmingham Biomedical and Scientific Research Ethics Committee. Local approval was obtained from: The Leprosy Mission Trust India Ethics Committee; Federal Capital Territory Health Research Ethics Committee in Nigeria and the Health Research Ethics Committee of Niger State Ministry of Health; University of Nigeria Teaching Hospital and the Nepal Health and Research Council. Results will be disseminated via peer-reviewed journals, conference presentations and community engagement events through the leprosy missions. [Abstract copyright: © Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

Quantifying Rates of Evolutionary Adaptation in Response to Ocean Acidification

The global acidification of the earth's oceans is predicted to impact biodiversity via physiological effects impacting growth, survival, reproduction, and immunology, leading to changes in species abundances and global distributions. However, the degree to which these changes will play out critically depends on the evolutionary rate at which populations will respond to natural selection imposed by ocean acidification, which remains largely unquantified. Here we measure the potential for an evolutionary response to ocean acidification in larval development rate in two coastal invertebrates using a full-factorial breeding design. We show that the sea urchin species Strongylocentrotus franciscanus has vastly greater levels of phenotypic and genetic variation for larval size in future CO2 conditions compared to the mussel species Mytilus trossulus. Using these measures we demonstrate that S. franciscanus may have faster evolutionary responses within 50 years of the onset of predicted year-2100 CO2 conditions despite having lower population turnover rates. Our comparisons suggest that information on genetic variation, phenotypic variation, and key demographic parameters, may lend valuable insight into relative evolutionary potentials across a large number of species

Mortality Surveillance Methods to Identify and Characterize Deaths in Child Health and Mortality Prevention Surveillance Network Sites

Despite reductions over the past 2 decades, childhood mortality remains high in low- and middle-income countries in sub-Saharan Africa and South Asia. In these settings, children often die at home, without contact with the health system, and are neither accounted for, nor attributed with a cause of death. In addition, when cause of death determinations occur, they often use nonspecific methods. Consequently, findings from models currently utilized to build national and global estimates of causes of death are associated with substantial uncertainty. Higher-quality data would enable stakeholders to effectively target interventions for the leading causes of childhood mortality, a critical component to achieving the Sustainable Development Goals by eliminating preventable perinatal and childhood deaths. The Child Health and Mortality Prevention Surveillance (CHAMPS) Network tracks the causes of under-5 mortality and stillbirths at sites in sub-Saharan Africa and South Asia through comprehensive mortality surveillance, utilizing minimally invasive tissue sampling (MITS), postmortem laboratory and pathology testing, verbal autopsy, and clinical and demographic data. CHAMPS sites have established facility- and community-based mortality notification systems, which aim to report potentially eligible deaths, defined as under-5 deaths and stillbirths within a defined catchment area, within 24-36 hours so that MITS can be conducted quickly after death. Where MITS has been conducted, a final cause of death is determined by an expert review panel. Data on cause of death will be provided to local, national, and global stakeholders to inform strategies to reduce perinatal and childhood mortality in sub-Saharan Africa and South Asia

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

The leadership of Ross O. Swimmer, 1975-1985 : a case study of a modern Cherokee principal chief

textThe following study examined leadership characteristics of a modern leader of the Cherokee Nation, Ross O. Swimmer, during his three elections as Principal Chief, 1975-1985. Few Western scholars paid attention to the Cherokee Tribe after the break-up of institutions legislated by the federal Indian policy of Allotment. The position of the government was, the Cherokee Tribe no longer existed. For almost seventy years, no form of Cherokee leadership was visible; no Cherokee government existed. Federal Indian policy changed again, allowing tribes to elect their own leaders. This study began filling in gaps of missing information on modern Cherokee leadership by examining Swimmer’s leadership characteristics. The study attempted to add to the body of leadership knowledge by mining minds and memories, searching for the meaning of leadership from a modern Cherokee perspective. The three questions guiding the study were: what were the leadership characteristics of Principal Chief Ross O. Swimmer; to what extent did these leadership characteristics reflect traditional Cherokee leadership characteristics; and from a tribal perspective, did these make a difference, and to what extent? The data indicate seven Swimmer leadership characteristics: Visionary, Goal Oriented, Bureaucratic, Top-Down, Authoritarian, Delegator, and Communicator. There was inconsistency with Swimmer’s use of traditional leadership practices. Swimmer used a combination of traditional Cherokee, traditional Native American, and Anglo-European-American leadership characteristics during his three terms as Principal Chief of the Cherokee Nation. Two possible explanations for Swimmer’s blending leadership characteristics from varying models were suggested. First, given his bi-cultural heritage, Swimmer could navigate back and forth between the mainstream White culture and the traditional Cherokee culture, to pick and choose various types of leadership characteristics. Second, adaptability has always been a unique characteristic of the Cherokee people. Cherokee leaders frequently applied the feature of borrowing from White culture in order to adapt and survive. Swimmer accomplished many of his goals for the Cherokee people and set the Nation on a path of growth and stability. His methods were not without criticism from traditional Cherokees. However, Swimmer built the foundation for a corporate government that instilled pride in the Cherokee people and provided opportunity for self-sufficiency.Educational Administratio

A comparative study of the physico-chemical properties and methylene blue adsorption behaviour of fly ash, nano-oxides and the composite materials of nano-oxides and fly ash.

In this present study, composite materials involving fly ash produced from coal combustion and nano-oxides were prepared. The nature, morphology and properties of the precursors and the composite materials were determined by modern instrumental analytical techniques such as carbon, nitrogen and hydrogen (CNH) analysis, Brunauer–Emmett–Teller (BET) surface area and porosity analysis, scanning and transmission electron microscopy, and x-ray diffraction. Particle size distribution, ash content, pH and point of zero charge were also investigated. The adsorption kinetics of methylene blue (MB) onto these adsorbents was examined. Experimental results showed that the composition of fly ash and nano-oxides contributed to the development of intergranular voids and crevices with high surface and micropore areas that enhanced the adsorption of MB from an aqueous solution. The adsorption of MB onto the precursors and the composite materials follow the pseudo-second order kinetic model