Receipt from D. Brown & Co. to Ogden Goelet

https://digitalcommons.salve.edu/ochre-court/1188/thumbnail.jp

Understanding corrosion features and alloy microstructural effects on fatigue initiation of corroded AA7050-T7451 using data science

Aluminum alloy 7050-T451 is generally used in aerospace structure due to its high strength-to-weight ratio and high toughness. Local galvanic coupling set up by wicking of electrolyte in between the stainless steel fastener used in the aircrafts and the aluminum substructure promote corrosion of AA7050-T7451. Fatigue crack initiation tend to occur on discontinuities in the aluminum alloy such as the corrosion damage created by the galvanic coupling. Previous study indicate that the individual metrics analyzed for the macro-scale (\u3e250 μm) corrosion features such as pit depth, pit density, pit volume, area of the pit mouth, do not fully correlate to the location of the fatigue crack initiation [1]. The objective of this study is to verify if there is an interaction effect on the metrics analyzed using the macro-scale corrosion damage features using data science techniques. Another objective of this study is to determine if the micro-scale (\u3c250 μm) corrosion features and the alloy microstructure play an important role in the fatigue initiation mechanism of AA7050-T7451. In order to understand the mechanism governing the fatigue crack formation, corrosion damage mimicking the galvanic coupling effect of AA7050-T7451 and SS316 are artificially created on the surface of AA7050-T7451. A small area on the LS surface of the fatigue specimens are exposed to different environmental conditions to create four different corrosion morphologies, namely, shallow and deep discrete pits, fissures and general corrosion with surface recession. These corrosion morphologies are characterized using the optical microscope, white light interferometer, scanning electron microscope and X-ray computed tomography. The specimens are subjected to fatigue loading using a special loading protocol that creates marker bands on the fracture surface. The specimens are cyclically loaded along the L-direction with σmax of 200 MPa, R ratio of 0.5 at a frequency of 20 Hz. The fatigue testing is done at 23°C and a controlled moist environment with \u3e90% relative humidity during the entire test. After fatigue testing, the fractographs of the specimens are obtained using the SEM. The marker bands from these fractographs are analyzed to calculate the crack growth rate and the fatigue initiation life to create a 10 μm crack from the initiation point are estimated. Data science approaches are employed to analyze the interaction effect of the individual metrics reported in the macro-scale corrosion feature analysis. Random forest and logistic regression modeling show that there is minimal significance between the macro-scale corrosion feature predictor variables and the fatigue crack initiation points. Even though data science indicate that these factors have less significance, these factors should not be neglected. The micro-scale corrosion features and the distribution of secondary phase particles as well as the grain character are individually analyzed and correlated to the location of the fatigue crack initiation for all the corrosion damage morphologies. Results show that these individual metrics does not fully dictate the location of the fatigue crack initiation. Future work of this study involves the use of data science techniques to understand the relationship between the micro-scale corrosion features, their possible interaction with the alloy microstructure, and the fatigue crack formation. This study will provide understanding on what governs the fatigue crack initiation and inform current micro-mechanical models to incorporate effects of pertinent parameters in predicting remaining life of corroded specimens. Reference: [1] Co NEC, Burns JT. Effects of macro-scale corrosion damage feature on fatigue crack initiation and fatigue behavior. Int J Fatigue 2017;103:234–47. doi:10.1016/j.ijfatigue.2017.05.028

Short-range correlations and meson exchange currents in photonucleon emission

One-nucleon emission processes induced by photon absorption are studied by considering short-range correlations effects. At energies above the giant resonance region the validity of the direct knock-out model has been tested by comparison with continuum Random Phase Approximation results. Nucleon re-scattering effects have been considered by using an optical potential. The role of the electromagnetic convection, magnetization and meson exchange currents has been investigated as a function of both excitation energy and momentum transfer. The short-range correlation effects have been studied by using various correlation functions. We found that the nucleon photo-emission cross section is rather sensitive to the presence of short-range correlations at large values of nucleon emission angle. In this region, however, the effects of meson exchange currents are even larger than those produced by short-range correlations.Comment: 37 pages, 20 figures in postscript, Text in LaTe

In vitro study of the interaction between some fluoroquinolones and extracts of kola nitida seed

The cup diffusion method (CD) was used to evaluate the in vitro interaction of some fluoroquinolones (ciprofloxacin, pefloxacin and levofloxacin) with extracts of Kola nitida seed (KNS) against a clinical isolate of Escherichia coli. Minimum inhibitory concentration (MIC) of the drugs was determinedseparately and in combination with KNS extract in ratios of 0:5, 1:4, 2:3, 3:2, 4:1 and 5:0 against E. coli. The result of the study revealed that the MIC of the drugs decreased when combined with KNS extract. In other words, KNS extract potentiated the effects of the fluoroquinolones against E. coli

Investigating Differences in Nutritional Parameters in Ugandan Children with Plasmodium falciparum Severe Malaria

Background: The past two decades have witnessed a 60% decline in global malaria mortality. However, two thirds of all malaria deaths continue to occur among children <5 years, with a majority in the WHO African Region. Malnutrition is an important risk factor for malaria. Wasting, Stunting and Underweight are crucial indicators of malnutrition, and are associated with increased mortality in children <5. Annually, 14 million children <5 are classified as wasted and 59 million children are classified as stunted. Objective: The objective of this study is to look at nutritional parameters, weight-for-age (WAZ), height-for-age (HAZ), and weight-for-height (WHZ), and how they differ over time in children <5 with severe malaria (SM) from the Ugandan cities Mulago and Jinja and the outcomes of mortality and nutritional parameters, underweight, stunting, and wasting. Methods: We defined underweight, stunting, and wasting as 2SD below the WAZ, HAZ, and WHZ means. We evaluated Z-scores and mortality status from children <5 years enrolled in a prospective cohort study (NDI, Neurodevelopmental Impairment in Children with Severe Malaria) at enrollment and 12-month follow-up between two sites. Results: WAZ, HAZ and WHZ at baseline were significantly lower among SM groups than in CC (p<0.01), and the SM group maintained significantly lower WHZ (p<0.01) and HAZ (p<0.001) at 12-month follow-up. Among the children who died, there were no significant differences of nutritional markers in Mulago, but in Jinja there was found to be a significant association between mortality and low WAZ (p<0.05) and underweight (p<0.05). Of children classified as underweight in Jinja, 37.5% of them died compared to 15.9% who survived; additionally, the odds ratio for decreased WAZ and mortality was 0.58 (p<0.05). Conclusion: Underweight, stunting, and wasting may be risk factors for SM, and underweight may exacerbate poor mortality outcomes in rural areas like Jinja. While underweight is worsened among children with SM at 1 month and normalizes by 12 months, stunting remains persistently low at 12 months. Nutritional interventions must be aimed at maintaining linear growth throughout the first year of SM in children <5 to reduce the risk factor of underweight on poor mortality outcomes

Portrait of Abraham Lincoln, President 1861-1865

A black and white portrait illustration of Abraham Lincoln from Brown\u27s Famous Pictures collection. The print was found behind another print (inventory # 6981) in a frame, but was removed for preservation.https://scholarsjunction.msstate.edu/fvw-prints/1190/thumbnail.jp

A study of the in vitro interaction of cotrimoxazole and ampicillin using the checkerboard method

In this study, the in vitro interaction of two standard antibiotics – cotrimoxazole and ampicillin trihydrate were studied by the checkerboard technique, using clinical isolates of P. aeruginosa, Staphylococcus aureus and Salmonella typhi. The organisms were exposed to the individual antibiotics as well as different combination ratios of the same, and the zones of inhibition as well as the minimum inhibitory concentrations (MICs) measured. Synergistic interactions were recorded by the antibiotics against Staph. aureus and S. typhi while indifferent interaction occurred with P. aeruginosa. P. aeruginosa however, showed resistance to the two antibiotics when they were used alone. The implication is that cotrimoxazole and ampicillin can be used in combination as a superior treatment of infections caused by Staph. aureus and S. typhi

Coulomb Distortion in Quasielastic (e,e′)(e,e') Scattering on Nuclei: Effective Momentum Approximation and Beyond

The role of the effective momentum approximation to disentangle Coulomb distortion effects in quasielastic $(e,e')$ reactions is investigated. The separation of the cross section in longitudinal and transverse components is discussed including higher order DWBA corrections due to the focusing of the electron waves.The experimental studies performed, in the last few years, making use of different approximate treatments are shown to be sometime inconsistent. As a consequence some of the longitudinal and transverse responses, extracted from the inclusive cross sections cannot be considered reliable. A separation procedure based on the effective momentum approximation is discussed in connection with the recent experimental data on electron/positron quasielastic scattering on $^{12}$C and $^{208}$Pb.Comment: latex, no figures, submitted to Nucl. Phys.

Disaster Management Education through Higher Education – Industry Collaboration in the Built Environment

Effectively responding to the current and dynamic construction labour market requirements is a major responsibility of higher education institutions (HEIs). HEIs aim to reduce the mismatch between what they deliver and what is required by the industry. Built environment professionals require continuous update of knowledge and education in order to effectively contribute to disaster management. However, the complex and multidisciplinary nature of disaster management education pose a challenge to the higher education institutions to make them more responsive to the industrial needs and to prepare the students for careers in disaster resilience. Adopting a lifelong learning approach would be appropriate for HEIs to maintain a through-life studentship and to provide disaster related knowledge and education on a continuous basis to respond to the labour market requirements. However, incorporating lifelong learning approach within the system of higher education is not easy and straightforward for HEIs. This is mainly because of the formal and bureaucratic nature of HEIs that acts as a barrier for providing effective lifelong learning education. In resolving this issue, HEIs are increasingly relying on the benefits associated with fostering close collaboration with external organisations such as industries, professional bodies and communities. In this context, this paper discusses the role of HEIs in providing disaster management education, the challenges associated with it, and the way of addressing the challenges through the higher education industry collaboration

Scholarship funding through strategic reporting: the case of Koro Island

This study used observational and textual analysis to ascertain how the Koro Island Scholarship Fund developed a reporting model to access funding for educational scholarships that facilitated access to high schooling for disadvantaged children in the Lomaiviti Group of Eastern Fiji. The reporting model also provided information to key stakeholders, such as donor groups and aid organizations, for the assessment of student and funding performance. It appears sound financial accountability of a scholarship fund is welcomed by donors. The scholarship fund appeared to work well if there was limited intrusion into the operations of a donee school, providing space for interrelations between traditional Fijian school values, the island landscape and the local conventions and customs