A numerical and experimental investigation into residual stress in thermally sprayed coatings

AbstractThis paper is concerned with an investigation into the thermal spray process and is particularly concerned with the residual stresses that arise when a steel-alloy coating is sprayed onto a copper-alloy substrate. This material combination was used recently to enhance the thermal and mechanical efficiency of the pressure die casting process. A difficulty with the spraying of steel on copper is the attainment of appreciable thickness of the coating due to debonding during the thermal spraying process. Prominent among possible causes of debonding is residual stress, which is the focus of the research presented in the paper. An investigation into the thermal spray process is performed using experimentation, simplified numerical modelling and finite element modelling. The development of residual stress for a range of process parameters, i.e. deposited layer thickness, interval of layer deposition and the number of layers in a coating (i.e. block deposition versus multilayer deposition for a desired coating thickness) is recorded. The results from the three investigation methods agreeably indicate a progressive change in average interfacial residual stress from compressive towards tensile with increase in thickness of deposited layer; and a tensile interfacial stress in a two-layer coating, which increases with increase in interval of deposition between the two layers. On the whole, the observations from the results suggest an increase in potential for coating debonding with increase in both deposited layer thickness and layer deposition interval. The results further suggest higher potential for coating debonding with block deposition compared to multilayer deposition for a desired coating thickness

CASE REPORT: A GIANT URINARY BLADDER STONE IN A FEMALE PATIENT

A vesical calculus weighing more than 100g is categorized as a giant urinary bladder stone. Male preponderance for urinary bladder calculi is well known. A rare case of a giant urinary bladder calculus weighing 1200g and occurring in a female patient is reported. The stone was removed by open vesicolithotomy

Science-based decision support for formulating crop fertilizer recommendations in sub-Saharan Africa

Open Access Article; Published online: 31 Jan 2020In sub-Saharan Africa, there is considerable spatial and temporal variability in relations between nutrient application and crop yield, due to varying inherent soil nutrients supply, soil moisture, crop management and germplasm. This variability affects fertilizer use efficiency and crop productivity. Therefore, development of decision systems that support formulation and delivery of site-specific fertilizer recommendations is important for increased crop yield and environmental protection. Nutrient Expert (NE) is a computer-based decision support system, which enables extension advisers to generate field- or area-specific fertilizer recommendations based on yield response to fertilizer and nutrient use efficiency. We calibrated NE for major maize agroecological zones in Nigeria, Ethiopia and Tanzania, with data generated from 735 on-farm nutrient omission trials conducted between 2015 and 2017. Between 2016 and 2018, 368 NE performance trials were conducted across the three countries in which recommendations generated with NE were evaluated relative to soil-test based recommendations, the current blanket fertilizer recommendations and a control with no fertilizer applied. Although maize yield response to fertilizer differed with geographic location; on average, maize yield response to nitrogen (N), phosphorus (P) and potassium (K) were respectively 2.4, 1.6 and 0.2 t ha−1 in Nigeria, 2.3, 0.9 and 0.2 t ha−1 in Ethiopia, and 1.5, 0.8 and 0.2 t ha−1 in Tanzania. Secondary and micronutrients increased maize yield only in specific areas in each country. Agronomic use efficiencies of N were 18, 22 and 13 kg grain kg−1 N, on average, in Nigeria, Ethiopia and Tanzania, respectively. In Nigeria, NE recommended lower amounts of P by 9 and 11 kg ha−1 and K by 24 and 38 kg ha−1 than soil-test based and regional fertilizer recommendations, respectively. Yet maize yield (4 t ha−1) was similar among the three methods. Agronomic use efficiencies of P and K (300 and 250 kg kg−1, respectively) were higher with NE than with the blanket recommendation (150 and 70 kg kg−1). In Ethiopia, NE and soil-test based respectively recommended lower amounts of P by 8 and 19 kg ha−1 than the blanket recommendations, but maize yield (6 t ha−1) was similar among the three methods. Overall, fertilizer recommendations generated with NE maintained high maize yield, but at a lower fertilizer input cost than conventional methods. NE was effective as a simple and cost-effective decision support tool for fine-tuning fertilizer recommendations to farm-specific conditions and offers an alternative to soil testing, which is hardly available to most smallholder farmers

Factors associated with under-5 mortality in three disadvantaged East African districts

BACKGROUND: The high rate of avoidable child mortality in disadvantaged communities in Africa is an important health problem. This article examines factors associated with mortality in children 6 h away from the nearest health centre (6-23 h: AOR 1.66 [95% CI 1.4-2.0] and ?24 h: AOR 1.43 [95% CI 1.26-1.72]) reported higher mortality rates in children 6 h away from health centres and mothers who received inadequate ANC visits during pregnancy

Studi In Vitro Potensi Kurkuminoid (Curcuma Domestica Vahl) dan Senyawa-senyawanya terhadap Superoksidadismutase dan pada Proses Peroksidasi Lipid Sel Monosit.

Tujuan penelitian adalah untuk mengetahui apakah masing-masing sampel ( kurkuminoid,kurkumin, desmetoksikurkumin dan bisdesmetoksikurkumin ) dengan dosis sama (3,68 ug/50ul)yang diisolasi dan dimurnikan dari rimpang kunyit (Curcuma domestica Vahl) memiliki efekterhadap aktivitas superoksidadismutase dan terhadap proses peroksidasi lipid secara in vitro.Subjek penelitian menggunakan sel monosit yang diisolasi dari darah pria dewasa normaldengan metode Boyum.Masing-masing sampel dibagi ke dalam dua grup, grup (a) dilarutkan dalam dimetilsulfoksida(DMSO), dan grup (b) dilarutkan dalam air suling. Kedua grup sampel tersebut diuji terhadapaktivitas superoksidadismutase, dilakukan dengan metode Murakami, dan juga diuji terhadapproses peroksidasi lipid sel monosit dilakukan dengan metode TBARS.Hasil penelitian dari kedua grup sampel, memiliki efek meningkatkan aktivitassuperoksidadismutase secara bermakna (p< 0,05), demikian pula dapat menghambat terhadapproses peroksidasi lipid, yang ditunjukan dengan penurunan kadar malondialdehid secarabermakna (p< 0,05).Sampel grup (a) memiliki kekuatan lebih besar terhadap peningkatan aktivitas superoksidadismutasejika dibandingkan dengan sampel grup (b), khususnya terlihat pada kurkuminoidaktivitasnya hampir menyamai α-tokoferol.Kurkumin baik dari grup (a) maupun dari grup (b) memiliki aktivitas yang lebih besar terhadappenghambatan proses peroksidasi lipid dibandingkan dengan kurkuminoid, desmetoksikurkumindan bisdesmetoksi-kurkumin. Bahkan lebih kuat dari α-tokoferol

Governments' policy response to drought in Eswatini and Lesotho : a systematic review of the characteristics, comprehensiveness, and quality of existing policies to improve community resilience to drought hazards

The southern African kingdoms of Eswatini and Lesotho experience recurrent drought-induced disasters. Policies have been enacted, but no attempt has been made to synthesise the effects on disaster resilience. This review analyses the characteristics, quality, and comprehensiveness of drought-resilience policies in Eswatini and Lesotho. We have systematically reviewed public policies that shape responses to disaster resilience published between 1 January 1980 and 30 June 2019. A combination of keywords was used to search electronic bibliographic databases, multidisciplinary databases, key organisational websites, and the first 20 pages of Google for policies that addressed disaster and/or drought resilience. Identified documents were downloaded into an EndNote database and screened for eligibility using predetermined criteria. The logic of events framework was used for quality assessment, and a metaethnographic approach was applied for data synthesis. Three broad categories of characteristics, thematic outcomes and quality, and comprehensiveness of policy documents emerged and are presented. Policy responses contributing to disaster resilience were found in n = 32 out of 13,700 documents. Three (n = 3/32) policies were statutory, and the rest were nonstatutory. Eleven (n = 11/32) were assessed to be of high quality. Policy responses relating to drought resilience focused on reducing vulnerability to recurrent disasters; promoting drought and climate change adaptation; improving agriculture and food security; safeguarding cultural heritage; and preventing gender inequality and gender-based violence as well as improving disaster governance. However, the construct of drought resilience was not strongly articulated as a major policy goal across policy documents. There is an urgent need to promote better understanding of drought resilience in order to motivate policymakers to steer away from reactive interventions and position resilience as a major national policy goal in both countries to expedite inclusive growth and safeguard development gains and the health and wellbeing of the majority of their populations who are rural-based populations

The impact of the livelihoods and income fortification and socio-civic transformation project on the quality of life, wellbeing, self-esteem, and quality of neighbourhood social environment among the youth in slum areas of in Kampala, Uganda

Background: Various interventions to improve the quality of life (QoL) among slum dwellers across sub Saharan Africa have been implemented. However, the interventions impacts remain less understood. We assessed the impact of the Urban Program on Livelihoods and Income Fortification and Socio-civic Transformation (UPLIFT) project on QoL, psychological wellbeing, self-esteem, and the quality of neighbourhood social environment of young people aged 13–25 years in slum areas of Makindye and Nakawa Divisions in Kampala, Uganda. Methods: The study was designed as a mixed method evaluation using repeated cross-sectional survey and grounded theory in both the intervention and comparison communities. The intervention effect was estimated using the difference-in-differences Kernel propensity-score matching technique, with bootstrapping. The “rcs” option was used given that data were from repeated cross-sectional surveys. A thematic analysis was adopted for the qualitative data to triangulate and complement the quantitative data. Results: The UPLIFT project led to an improvement in QoL, psychological wellbeing, and self-esteem of young people. In terms of QoL, the project led to a six-percentage point increase in quality of living conditions scores (where higher scores reflect better living conditions; lower ones, worse living conditions). However, a negative effect was observed for personal independence whilst the project did not have any impact on social relations. In terms of self-esteem and psychological wellbeing, the project led to a 4.6-point increase in self-esteem scores, a 5.4-point increase in self-acceptance scores, a 5.3- point increase in purpose in life scores, a 5.7 - point increase in personal growth, and a 10.7-point increase in autonomy scores. However, the project had a negative effect on personal independence; and had no impact on environmental mastery and the quality of neighbourhood social environment. Conclusion: Functional community-owned assets accumulation and capacity building initiatives for young people in slum areas improved their psychological wellbeing and quality of life. However, such initiatives do not appear to address social relationships and personal independence of young people in slum areas

Material characterization studies on the laser beam formed AISI 1008 mild steel

Laser Beam Forming is a new non-contact method without the use of a die, to achieve deformation in metals, which traditionally involved the application of mechanical forces to change the shape and form of the material permanently. Laser forming causes deformation by introducing thermal stresses from an external heat source as opposed to the simple application of forces in mechanical forming. In this study, samples were formed mechanically by using a dynamic press brake machine, whereby, a punch and die apply the force. A 4.4 kW Nd:YAG laser system was used to form a second set of samples made from cold rolled AISI 1008 mild steel using laser forming. In this collaborative work involving researchers from the USA, South Africa and India, the mechanical and metallurgical properties of the unformed, mechanically formed and laser formed samples were experimentally investigated. The objective is to compare these properties amongst the different samples in order to analyze the impact of the varying methodologies especially the laser energy effects on the samples. The conclusions from these tests have provided valuable information on the applicability of laser forming to attain the appropriate surface modifications yielding the desired mechanical and metallurgical properties of the metal

An intra-COVID-19 assessment of hand hygiene facility, policy and staff compliance in two hospitals in Sierra Leone: is there a difference between regional and capital city hospitals?

Although hand hygiene (HH) is the most effective intervention to reduce the spread of infections, there are limited data on HH facilities, policy, and compliance in sub-Saharan Africa. This cross-sectional study is aimed at assessing HH using the WHO HH self-assessment framework, HH technical reference manual, and a modified infection control self-assessment tool in two hospitals in Sierra Leone. Only 10% and 9% of regional and capital city hospitals had running tap water, respectively. Veronica buckets were the resources for HH in 89% of units in the regional hospital and 92% of units in capital city hospital. Constant supply of soap and alcohol-based hand rub was available in 82% and 68%; and 74% and 79% of units in the capital city and regional hospitals, respectively. Only 10% of the units in both hospitals had hand-drying facilities and functional sinks. Overall HH compliance for the two hospitals was 18.6% and was higher in the regional (20.8%) than the capital city (17.0%) hospitals. The HH levels for the capital city and regional hospitals were 277.5 and 262.5 respectively. Despite the COVID-19 pandemic, there are still challenges with HH compliance in Sierra Leone. It is, therefore, necessary to strengthen the HH multi-modal strategy