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Recent research has shown that copper-alloy dies sprayed with a protective steel layer can potentially replace steel dies in the pressure die casting process for the purpose of rapid heat extraction. The deposited layer is required to withstand abrasion, thermal shock, and cyclic loading, and be resistant to debonding from the copper-die substrate. This paper is concerned with an experimental investigation into the application of the HIP process to ascertain its effectiveness towards enhancing the bond strength, hardness, and densification of chrome steel coatings on a copper substrate. A particular focus of the paper is on the use of partial encapsulation coupled with the use of ceramic paper whose purpose is to transfer the loading pressure and prevent bonding between the die and the encapsulation container. It is shown in the paper that partial encapsulation is effective and can be used to HIP localized regions of a die. The ceramic paper was shown to be effective in transmitting loading and has the added advantage of providing relatively good surface finish as compared with that obtained with ceramic powder. The results of the experimental trials show reduced porosity and increased bond strength with application of the HIP process. In addition hardness values are shown to be reduced to levels typically found in traditional die-tool steels.

Abstract Recent efforts have considered the feasibility of using copper dies protected with a thermally sprayed coating layer in pressure die casting processes. Although such dies offer considerable advantage over traditional designs, particularly improved processing times, a particular drawback is the poor quality of the deposited layer. The coating layer of wearresistant material, which can be deposited on to a die-cavity surface using an arc-wire thermalspray process, can exhibit undesirable porosity, cracks, and inclusions. This in turn can result in poor in-service performance with castings of poor surface quality or dies with a reduced life. As a route to identifying a suitable and effective coating treatment strategy to enhance coating performance on the die, the current paper presents work carried out to investigate the effectiveness of the hot isostatic pressing (HIP) process towards the healing of porosity (i.e. coating densification) in chrome-steel coating and the enhancement of its hardness and bond strength on chrome-copper substrates. The results of the investigation reveal significant improvement in coating densification and bond strength at all process conditions. Also investigated is the relationship between bond strength, densification, and HIP temperatures. The HIP process is also shown to reduce coating hardness to levels of hardness equivalent to that of traditional tool steel. On the whole, the investigation suggests that optimum performance could be achieved from chrome-steel coating on chrome-copper substrates if HIPped at a temperature of 925°C and a pressure of 100 MPa.

Abstract Residual stress in thermally sprayed coatings is known to cause a range of problems, notably debonding, cracking, and spallation. The focus in this paper is on the development of simple analytical models for the prediction of residual stress that arise from spraying a steel-alloy coating onto a copper-alloy substrate. This is a material combination that has been used recently to enhance the thermal and mechanical efficiency of the pressure die casting process although problems with debonding have been reported in the literature. Three analytical models are developed and investigated, where each represent combinations of assumptions for coating and substrate material behaviours during coating manufacture. The sensitivity of these combinations on residual stress, developed for a range of process parameters (deposited layer thickness, interval of layer deposition and the number of layers in a coating, i.e. block deposition versus multi-layer deposition for a desired coating thickness) is recorded. In agreement with experimental and finite-element modelling results from a previous study, the results from all the three models assessed in the current study indicate a progressive change in average interfacial residual stress from compressive towards tensile with an increase in the thickness of the deposited layer; and a tensile interfacial stress in a two-layer coating, which increases with an increase in the interval of deposition between the two layers. The observations from the results suggest an increase in potential for coating debonding with an increase in both deposited layer thickness and layer deposition interval. The results further suggest higher potential for coating debonding with block deposition compared with multi-layer deposition for a desired coating thickness. In terms of stress magnitudes, the model that performs best is one where the assumption that a currently deposited coating layer yields during its quenching phase and adopts elastic behaviour afterwards; and the strain generated in the substrate during the quenching phase is from thermal effect only while in the other phases afterwards, is from both thermal and elastic effects.

This paper reports the investigation of some metrological parameters on the efficiency of photovoltaic module in some areas in the Niger Delta region of Nigeria. Results obtained show that efficiency of solar panel is directly proportional to solar flux and output current. Also, that increase in solar flux results to increase in output current of solar panel and enhance efficiency. It was also observed that relative humidity reduces output current and increases efficiency.

Sierra Leone has very high maternal and neonatal mortality rates, and a large proportion of these deaths occur in adolescents, a particularly vulnerable group, and is usually driven by poverty, lack of education, and sparse employment opportunities. We evaluated the feasibility and potential effects of a community-based mentoring intervention from pregnancy up to 1 year after birth to inform a subsequent larger trial aiming to reduce mortality among adolescent girls and their newborns (2YoungLives). We conducted a parallel-arm, pilot, hybrid implementation–effectiveness cluster randomised controlled trial of the introduction of the 2YoungLives intervention as an adjunct to maternity care in rural and urban communities served by 12 peripheral health units in five districts of Sierra Leone. Clusters were randomly allocated 1:1. All pregnant adolescent girls aged younger than 18 years living in those cluster communities and presenting for maternity care were eligible. The primary outcome was a composite of maternal and perinatal deaths (including stillbirths and neonatal deaths), assessed in all randomly allocated participants who remained in follow-up. The trial was prospectively registered (ISRCTN32414369). Between July 4, 2022, and Nov 30, 2023, 673 girls were included in the trial; six clusters with 372 girls were allocated to 2YoungLives (intervention group; 361 included in primary analysis) and six clusters with 301 girls were allocated to the control group (279 included in primary analysis). Loss to follow-up accounted for less than 10% in both groups. The incidence of the primary composite outcome by intention to treat was significantly lower in the intervention group (23 [6%] of 361 compared with 35 [13%] of 279 in the control group [adjusted risk ratio 0·52, 95% CI 0·34 to 0·81, p=0·0034; risk difference –0·05%, 95% CI –0·10 to –0·01]). The number needed to treat with 2YoungLives to prevent one maternal or perinatal death was 18 (95% CI 10 to 92). 2YoungLives, a community-based mentoring intervention for adolescent girls from pregnancy up to 1 year after birth, was feasible to implement in urban and rural communities in Sierra Leone and significantly reduced a composite of maternal deaths, stillbirths and neonatal deaths. UK National Institute for Health and Care Research.

Background radiation from the use of photocopies, computers and other electronic devices around River State University of Science and Technology was measured using a specialize digital, radiation meter type, radalert - 50, which is optimized to detect radiations like alpha, beta, gamma and x-rays. Measurements were carried out within seven working hours of the day and for seven days of the week in each of the five locations selected evenly. Using a calibration factor linked to Cs-137, the values obtained in count per minute (CPM) were converted to dose equivalent rate in mSv/Week. Results show that an average radiation level of 2.87x10 super( -3) mSv/Week was prevalent. This is clearly below the recommended safety radiation limit of 2.0x10 super( -2) mSv/Week as prescribed by ICRP, hence no cause for alarm.

Vaccine hesitancy is a complex, contested social phenomenon and existing research highlights the multifaceted role of trust in strengthening vaccine confidence. However, understanding public engagement with vaccination through the lens of (mis)trust requires more contextual evidence on trust's qualitative determinants. This includes expanding the geographic focus beyond current studies' focus on High Income Countries. Furthermore, obstacles remain in effectively integrating social science findings in the design of vaccine deployment strategies, and in ensuring that those who implement interventions and are affected by them are directly involved in producing knowledge about vaccination challenges. We piloted a community-led ethnographic approach, training Community Health Workers (CHWs) in Kambia District, Sierra Leone, in qualitative social science methods. Methods included participant observation, participatory power mapping and rumour tracking, focus group discussions and key stakeholder interviews. CHWs, with the support of public health officials and professional social scientists, conducted research on vaccination challenges, analysed data, tested new community engagement strategies based on their findings and elicited local perspectives on these approaches. Our findings on vaccine confidence in five border communities highlighted three key themes: the impact of prior experiences with the health system on (mis)trust; relevance of livelihood strategies and power dynamics for vaccine uptake and access; and the contextual nature of knowledge around vaccines. Across these themes, we show how expressions of trust centered on social proximity, reliability and respect and the role of structural issues affecting both vaccine access and confidence. The pilot also highlighted the value and practical challenges to meaningfully co-designed research. There is scope for broader application of a community-led ethnographic approach will help redesign programming that is responsive to local knowledge and experience. Involving communities and low-cadre service providers in generating knowledge and solutions can strengthen relationships and sustain dialogue to bolster vaccine confidence.

In 2021, an operational research study in two tertiary hospitals in Freetown showed poor hand hygiene compliance. Recommended actions were taken to improve the situation. Between February-April 2023, a cross-sectional study was conducted in the same two hospitals using the World Health Organization hand hygiene tool to assess and compare hand hygiene compliance with that observed between June-August 2021. In Connaught hospital, overall hand hygiene compliance improved from 51% to 60% ('p' < 0.001), and this applied to both handwash actions with soap and water and alcohol-based hand rub. Significant improvements were found in all hospital departments and amongst all healthcare worker cadres. In 34 Military Hospital (34MH), overall hand hygiene compliance decreased from 40% to 32% ('p' < 0.001), with significant decreases observed in all departments and amongst nurses and nursing students. The improvements in Connaught Hospital were probably because of more hand hygiene reminders, better handwash infrastructure and more frequent supervision assessments, compared with 34MH where interventions were less well applied, possibly due to the extensive hospital reconstruction at the time. In conclusion, recommendations from operational research in 2021 contributed towards the improved distribution of hand hygiene reminders, better handwash infrastructure and frequent supervision assessments, which possibly led to improved hand hygiene compliance in one of the two hospitals. These actions need to be strengthened, scaled-up and guided by ongoing operational research to promote good hand hygiene practices elsewhere in the country.

The Ebola epidemics in west Africa and the Democratic Republic of the Congo highlight an urgent need for safe and effective vaccines to prevent Ebola virus disease. We aimed to assess the safety and long-term immunogenicity of a two-dose heterologous vaccine regimen, comprising the adenovirus type 26 vector-based vaccine encoding the Ebola virus glycoprotein (Ad26.ZEBOV) and the modified vaccinia Ankara vector-based vaccine, encoding glycoproteins from Ebola virus, Sudan virus, and Marburg virus, and the nucleoprotein from the Tai Forest virus (MVA-BN-Filo), in Sierra Leone, a country previously affected by Ebola. The trial comprised two stages: an open-label, non-randomised stage 1, and a randomised, double-blind, controlled stage 2. The study was done at three clinics in Kambia district, Sierra Leone. In stage 1, healthy adults (aged ≥18 years) residing in or near Kambia district, received an intramuscular injection of Ad26.ZEBOV (5 × 1010 viral particles) on day 1 (first dose) followed by an intramuscular injection of MVA-BN-Filo (1 × 108 infectious units) on day 57 (second dose). An Ad26.ZEBOV booster vaccination was offered at 2 years after the first dose to stage 1 participants. The eligibility criteria for adult participants in stage 2 were consistent with stage 1 eligibility criteria. Stage 2 participants were randomly assigned (3:1), by computer-generated block randomisation (block size of eight) via an interactive web-response system, to receive either the Ebola vaccine regimen (Ad26.ZEBOV followed by MVA-BN-Filo) or an intramuscular injection of a single dose of meningococcal quadrivalent (serogroups A, C, W135, and Y) conjugate vaccine (MenACWY; first dose) followed by placebo on day 57 (second dose; control group). Study team personnel, except those with primary responsibility for study vaccine preparation, and participants were masked to study vaccine allocation. The primary outcome was the safety of the Ad26.ZEBOV and MVA-BN-Filo vaccine regimen, which was assessed in all participants who had received at least one dose of study vaccine. Safety was assessed as solicited local and systemic adverse events occurring in the first 7 days after each vaccination, unsolicited adverse events occurring in the first 28 days after each vaccination, and serious adverse events or immediate reportable events occurring up to each participant's last study visit. Secondary outcomes were to assess Ebola virus glycoprotein-specific binding antibody responses at 21 days after the second vaccine in a per-protocol set of participants (ie, those who had received both vaccinations within the protocol-defined time window, had at least one evaluable post-vaccination sample, and had no major protocol deviations that could have influenced the immune response) and to assess the safety and tolerability of the Ad26.ZEBOV booster vaccination in stage 1 participants who had received the booster dose. This study is registered at ClinicalTrials.gov, NCT02509494. Between Sept 30, 2015, and Oct 19, 2016, 443 participants (43 in stage 1 and 400 in stage 2) were enrolled; 341 participants assigned to receive the Ad26.ZEBOV and MVA-BN-Filo regimen and 102 participants assigned to receive the MenACWY and placebo regimen received at least one dose of study vaccine. Both regimens were well tolerated with no safety concerns. In stage 1, solicited local adverse events (mostly mild or moderate injection-site pain) were reported in 12 (28%) of 43 participants after Ad26.ZEBOV vaccination and in six (14%) participants after MVA-BN-Filo vaccination. In stage 2, solicited local adverse events were reported in 51 (17%) of 298 participants after Ad26.ZEBOV vaccination, in 58 (24%) of 246 after MVA-BN-Filo vaccination, in 17 (17%) of 102 after MenACWY vaccination, and in eight (9%) of 86 after placebo injection. In stage 1, solicited systemic adverse events were reported in 18 (42%) of 43 participants after Ad26.ZEBOV vaccination and in 17 (40%) after MVA-BN-Filo vaccination. In stage 2, solicited systemic adverse events were reported in 161 (54%) of 298 participants after Ad26.ZEBOV vaccination, in 107 (43%) of 246 after MVA-BN-Filo vaccination, in 51 (50%) of 102 after MenACWY vaccination, and in 39 (45%) of 86 after placebo injection. Solicited systemic adverse events in both stage 1 and 2 participants included mostly mild or moderate headache, myalgia, fatigue, and arthralgia. The most frequent unsolicited adverse event after the first dose was headache in stage 1 and malaria in stage 2. Malaria was the most frequent unsolicited adverse event after the second dose in both stage 1 and 2. No serious adverse event was considered related to the study vaccine, and no immediate reportable events were observed. In stage 1, the safety profile after the booster vaccination was not notably different to that observed after the first dose. Vaccine-induced humoral immune responses were observed in 41 (98%) of 42 stage 1 participants (geometric mean binding antibody concentration 4784 ELISA units [EU]/mL [95% CI 3736–6125]) and in 176 (98%) of 179 stage 2 participants (3810 EU/mL [3312–4383]) at 21 days after the second vaccination. The Ad26.ZEBOV and MVA-BN-Filo vaccine regimen was well tolerated and immunogenic, with persistent humoral immune responses. These data support the use of this vaccine regimen for Ebola virus disease prophylaxis in adults. Innovative Medicines Initiative 2 Joint Undertaking and Janssen Vaccines & Prevention BV.