Influence of limestone addition on sodium sulphate activated blast furnace slag cements

The effect of limestone replacement in the reaction and phase assemblage evolution of two sodium sulfate activated slag cements was investigated. The slag composition and its reactivity influenced the reaction kinetics of these materials. Paste with limestone addition exhibited an acceleration in reaction kinetics, particularly for slowly reacting slags. Ettringite and an aluminium substituted calcium silicate hydrate were identified as main reaction products in these cements, independently of the slag type or limestone replacement level. No significant changes in phase assemblages were observed with limestone addition for over 365 days of testing; however, these composite cements exhibited an increased compressive strength, consistent with a refined pore structure. These results indicate that it is possible to partially replace slag by limestone in sulfate activated slag cements without changing the type of reaction products forming in these systems, while also increasing compressive strength and achieving a similar refined pore structure

Measuring naturally acquired immune responses to candidate malaria vaccine antigens in Ghanaian adults

<p>Abstract</p> <p>Background</p> <p>To prepare field sites for malaria vaccine trials, it is important to determine baseline antibody and T cell responses to candidate malaria vaccine antigens. Assessing T cell responses is especially challenging, given genetic restriction, low responses observed in endemic areas, their variability over time, potential suppression by parasitaemia and the intrinsic variability of the assays.</p> <p>Methods</p> <p>In Part A of this study, antibody titres were measured in adults from urban and rural communities in Ghana to recombinant <it>Plasmodium falciparum </it>CSP, SSP2/TRAP, LSA1, EXP1, MSP1, MSP3 and EBA175 by ELISA, and to sporozoites and infected erythrocytes by IFA. Positive ELISA responses were determined using two methods. T cell responses to defined CD8 or CD4 T cell epitopes from CSP, SSP2/TRAP, LSA1 and EXP1 were measured by <it>ex vivo </it>IFN-γ ELISpot assays using HLA-matched Class I- and DR-restricted synthetic peptides. In Part B, the reproducibility of the ELISpot assay to CSP and AMA1 was measured by repeating assays of individual samples using peptide pools and low, medium or high stringency criteria for defining positive responses, and by comparing samples collected two weeks apart.</p> <p>Results</p> <p>In Part A, positive antibody responses varied widely from 17%-100%, according to the antigen and statistical method, with blood stage antigens showing more frequent and higher magnitude responses. ELISA titres were higher in rural subjects, while IFA titres and the frequencies and magnitudes of e<it>x vivo </it>ELISpot activities were similar in both communities. DR-restricted peptides showed stronger responses than Class I-restricted peptides. In Part B, the most stringent statistical criteria gave the fewest, and the least stringent the most positive responses, with reproducibility slightly higher using the least stringent method when assays were repeated. Results varied significantly between the two-week time-points for many participants.</p> <p>Conclusions</p> <p>All participants were positive for at least one malaria protein by ELISA, with results dependent on the criteria for positivity. Likewise, ELISpot responses varied among participants, but were relatively reproducible by the three methods tested, especially the least stringent, when assays were repeated. However, results often differed between samples taken two weeks apart, indicating significant biological variability over short intervals.</p

SARS-CoV-2 infections among asymptomatic individuals contributed to COVID-19 cases: A cross-sectional study among prospective air travelers from Ghana

BackgroundThe spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by asymptomatic individuals has been reported since the early stages of the coronavirus disease 2019 (COVID-19) outbreak in various parts of the world. However, there are limited data regarding SARS-CoV-2 among asymptomatic individuals in Ghana. The aim of the study was to use test data of prospective travelers from Ghana as a proxy to estimate the contribution of asymptomatic cases to the spread of COVID-19.MethodsThe study analyzed the SARS-CoV-2 PCR test data of clients whose purpose for testing was classified as “Travel” at the COVID-19 walk-in test center of the Noguchi Memorial Institute for Medical Research (NMIMR) from July 2020 to July 2021. These individuals requesting tests for travel generally had no clinical symptoms of COVID-19 at the time of testing. Data were processed and analyzed using Microsoft Excel office 16 and STATA version 16. Descriptive statistics were used to summarize data on test and demographic characteristics.ResultsOut of 42,997 samples tested at the center within that period, 28,384 (66.0%) were classified as “Travel” tests. Of these, 1,900 (6.7%) tested positive for SARS-CoV-2. The majority (64.8%) of the “Travel” tests were requested by men. The men recorded a SARS-CoV-2 positivity of 6.9% compared to the 6.4% observed among women. Test requests for SARS-CoV-2 were received from all regions of Ghana, with a majority (83.3%) received from the Greater Accra Region. Although the Eastern region recorded the highest SARS-CoV-2 positivity rate of 8.35%, the Greater Accra region contributed 81% to the total number of SARS-CoV-2 positive cases detected within the period of study.ConclusionOur study found substantial SARS-CoV-2 positivity among asymptomatic individuals who, without the requirement for a negative SARS-CoV-2 result for travel, would have no reason to test. These asymptomatic SARS-CoV-2-infected individuals could have traveled to other countries and unintentionally spread the virus. Our findings call for enhanced tracing and testing of asymptomatic contacts of individuals who tested positive for SARS-CoV-2

Community perspectives on persistent transmission of lymphatic filariasis in three hotspot districts in Ghana after 15 rounds of mass drug administration: a qualitative assessment

Abstract Background The Global Program for the Elimination of Lymphatic Filariasis (GPELF) started operation in 2000 and aimed at eliminating the disease by the year 2020, following 5–6 rounds of effective annual Mass Drug Administration (MDA). The MDA programme took off in Ghana in 2001 and has interrupted transmission in many areas while it has persisted in some areas after 10 or more rounds of MDA. This study was to appreciate community members’ perspectives on MDA after over 15 years of implementation. Findings will inform strategies to mobilise community members to participate fully in MDA to enhance the disease elimination process. Methods This was a qualitative study, employing key-informant in-depth-interviews. Respondents were selected based on their recognition by community members as opinion leaders and persons who were knowledgeable about the topic of interest in the community. A snowball sampling technique was used to select respondents. Results Respondents were well informed about the MDA with most of them saying, it has been implemented for over 12 years. They were aware that the MDA was for the treatment/control of LF (elephantiasis). It came to light that MDA compliance was affected by five related barriers. These are; Medication, Personal, Health system, Disease and Social structure related barriers. Adverse effects of the drugs and the fact that many people perceived that they were not susceptibility to the infection have grossly affected the ingestion of the drugs. Conclusion There is a need for community mobilization and promotional activities to explain the expected adverse reactions associated with the drugs to the people. Also the importance of why every qualified person in the community must comply with MDA must be emphasized

Dataset for 'Influence of limestone addition on sodium sulphate activated blast furnace slag cements'

The data contained in this workbook has been used to create the following figures in the journal article: Marsh, A.T., Yue, Z., Dhandapani, Y., Button, K., Adu-Amankwah, S. and Bernal, S.A., 2022. Influence of limestone addition on sodium sulphate activated blast furnace slag cements. Construction and Building Materials, 360, p.129527. https://doi.org/10.1016/j.conbuildmat.2022.12952

Accelerating early age properties of ultra-low clinker cements for extrusion-based 3D printing

In this study, we investigated the influence of commercial sodium nitrate/thiocyanate accelerator compared to calcium sulfoaluminate cement addition on setting time, rheology and reaction kinetics of ultra-low clinker composite cement for extrusion-based 3D printing application. CEM I 52.5 N and a ternary composite cement with 70% clinker replaced by slag and limestone were evaluated. Results indicate that final setting time of 30 min and buildable yield stresses can be attained with less than 5% addition of calcium sulfoaluminate, with ettringite and C-(A)-S-H as main reaction products. This demonstrates the synergy between slag and calcium sulfoaluminate cements can be harnessed to control rheology and hardening. This is significance for evidencing suitability of ultra-low clinker composite cements for extrusion-based 3DCP, thus helping to fulfil its wider potential as a low-carbon concrete technology

Safety and Immunogenicity of EBA-175 RII-NG Malaria Vaccine Administered Intramuscularly in Semi-Immune Adults: A Phase 1, Double-Blinded Placebo Controlled Dosage Escalation Study

<div><p>The erythrocyte binding antigen region II (EBA-175 RII) is a <i>Plasmodium falciparum</i> ligand that mediates erythrocyte invasion and is considered an important malaria vaccine candidate. A phase Ia trial in malaria naïve adults living in the United States found the recombinant non-glycosylated vaccine antigen, EBA-175 RII-NG adjuvanted with aluminium phosphate to be safe, immunogenic and capable of inducing biologically active antibodies that can inhibit parasite growth <i>in vitro</i>. The aim of the current study was to assess the safety and immunogenicity of this vaccine in malaria exposed semi-immune healthy adults living in a malaria endemic country, Ghana. In this double-blinded, placebo controlled, dose escalation phase I trial, eighteen subjects per group received ascending dose concentrations (5 μg, 20 μg or 80 μg) of the vaccine intramuscularly at 0, 1 and 6 months, while 6 subjects received placebo (normal saline). The primary end point was the number of subjects experiencing Grade 3 systemic or local adverse events within 14 days post-vaccination. Serious adverse events were assessed throughout the study period. Blood samples for immunological analyses were collected at days 0, 14, 28, 42, 180 and 194. A total of 52 subjects received three doses of the vaccine in the respective groups. No serious adverse events were reported. The majority of all adverse events reported were mild to moderate in severity, with local pain and tenderness being the most common. All adverse events, irrespective of severity, resolved without any sequelae. Subjects who received any of the EBA-175 RII-NG doses had high immunoglobulin G levels which moderately inhibited <i>P</i>. <i>falciparum</i> growth <i>in vitro</i>, compared to those in the placebo group. In conclusion, the EBA-175 RII-NG vaccine was safe, well tolerated and immunogenic in malaria semi-immune Ghanaian adults. Its further development is recommended.</p><p>Trial registration</p><p>ClinicalTrials.gov. Identifier: <a href="https://clinicaltrials.gov/ct2/show/NCT01026246" target="_blank">NCT01026246</a></p></div

Observed laboratory adverse events for all dose escalation groups.

<p><b>Panel A</b> is for screening prior to enrolment; <b>Panels B</b> and <b>C</b> are for vaccination 1, Day 0 and Day 14 respectively; <b>Panels D</b> and <b>E</b> are for vaccination 2, Day 0 and Day 14 respectively and <b>Panels F, G</b> and <b>H</b> are for vaccination 3, Day 0, Day 14 and Day 28 respectively. Abbreviations: ALT—Alanine Transaminase; AST—Alanine Aminotransferase; CR–Creatinine; BG–Blood glucose; K–Potassium; Na–Sodium; Hb–Hemoglobin; PLT–Platelets; WBC–White Blood Cells.</p

Demographic and baseline characteristics by dose of study population.

<p>Demographic and baseline characteristics by dose of study population.</p