Laboratory evaluation of the flotation response of a copper cobalt oxide ore to gasoil-rinkalore mixtures

Froth flotation remains to date as one of the most used metallurgical processes for concentrating metal-bearing minerals in ores. Oxide ores are relatively less amenable to froth flotation and require a judicious choice of reagents for the recovery of metals to be optimised. Laboratory batch flotation tests were conducted to determine the effect of two types of gasoil-rinkalore mixtures on the flotation response of a copper cobalt oxide ore sample. The head assay conducted on the initial ore sample showed that it contained about 2.90% of Cu, 0.12% of Co. Upon the flotation test work, the results obtained indicated that the concentrate obtained with use of the mixture gasoil-rinkalore RX yielded 8.24% Cu and 0.22% Co concentrate grades with recoveries of 76.0% Cu and 78.0% Co respectively. But, the concentrate obtained by use of the mixture gazoil-rinkalore RX3 yielded relatively bad results with 5.92% Cu and 0.18% Cu concentrate grades with recoveries of 70.3% Cu and 65.3% Co respectively

Leçons apprises de la gestion des épidémies de la maladie à virus Ebola en République Démocratique du Congo de 2007 à 2017: Lessons learned from the management of Ebola outbreaks in the Democratic Republic of Congo from 2007 to 2017

Context and objective. DRC’s ecosystem provides conditions that are favorable to the occurrence of zoonotic diseases at the human-animal interface including Ebola virus disease (EVD). Because the level of lethality of EVD is high, the present study focuses on the epidemics that occurred in Mweka (2007 and 2008), Isiro (2012), Boende (2014) and Likati (2017) with a view to assess the response components during each outbreak and to identify those with relevant impact on the scale of the epidemic. Methods. An analytical retrospective study of secondary data collected during the management of the five aforementioned EVD epidemics in DRC was conducted.Charecteristics of each outbreak were described based on descriptive statistics, and univariate analyzes of each response component were conducted in relation to lethality. Results. A total of 422 cases were recorded with 282 deaths or 66.8% lethality. The vast majority of cases are in the 15 to 49 age group. The female sex is the most represented. Among all the elements of the answer, in a univariate model, the deployment of the mobile laboratory (p = 0.002), the functionality of the commissions (p =0.001), the deployment of a multidisciplinary team and the powerful surveillance system (p = 0.001) are significantly associated with lethality. Conclusion. Rapid deployment of the mobile laboratory in the field, deployment of multidisciplinary teams, efficient functionality of the commissions and a functional monitoring system significantly reduced the fatality rate. Contexte et objectifs. La RDC a un écosystème favorable à la survenue des maladies d’origine zoonotique à l’interface homme-animal dont la maladie à virus Ebola (MVE). Face à une létalité reconnue être élevée pour cette dernière, cette étude s’est focalisée sur les épidémies survenues à Mweka (2007 et 2008), à Isiro (2012), à Boende (2014) et à Likati (2017) afin de décrire les différents éléments de réponse mis en place lors de chacune de ces épidémies et identifier ceux qui ont une influence significative sur l’ampleur de l’épidémie. Méthodes. Une étude documentaire analytique sur les données secondaires recueillies lors de la gestion de ces cinq épidémies de la MVE survenues en RDC. Les statistiques descriptives ont été réalisées pour caractériser chaque épidémie. Les analyses univariées de chaque élément de réponse ont été menées en rapport avec la létalité. Résultats. Un total de 422 cas a été enregistré avec 282 décès soit 66,8 % de létalité. La grande majorité de cas se trouve dans la tranche d’âge de 15 à 49 ans. Le sexe féminin est le plus représenté. Parmi tous les éléments de la réponse, dans un modèle univarié, le déploiement du laboratoire mobile (p=0,002), la fonctionnalité des commissions (p=0,001), le déploiement d’une équipe multidisciplinaire et le système de surveillance performant (p=0,001) sont associés significativement à la létalité. Conclusion. Le déploiement rapide du laboratoire mobile sur le terrain, le déploiement des équipes multidisciplinaires, la bonne fonctionnalité des commissions et le système de surveillance fonctionnel ont permis de réduire significativement la létalité

Empirical examination of herding behaviour in the Johannesburg stock exchange : a sectoral analysis

Abstract: This paper uses the daily stock returns from January 2010 to September 2015 to investigate the presence of herding behavior and its dynamics on the South African financial sector. The paper makes use of the median as an alternative proxy to the mean in estimating market average returns. We found evidence in support of herding behaviour in the general financials and the real estate sectors of the Johannesburg Stock Exchange (JSE) during normal market period. Investors in the banking and the insurance sectors were found to show rational investment decisions during all market periods

Tracking the railway line in-service behaviour through metallurgical and mechanical property characterisation

Wear, contact-impact, fatigue and corrosion properties are important factors initiating rail track degradation and are composition dependent. This work focuses on the effect of chromium content on the metallurgical and mechanical properties of the the rail steels. Two medium steel railway tracks differing in their chromium content, alloy MS02 with 0.02 wt% Cr and alloy MS03 containing 0.72 wt% Cr, were characterised in order to predict their in-service performance as a function of their chemical composition. The microstructural analysis revealed in MS02 a relatively coarser grain size, consisting of pearlite and grain boundary ferrite. MS03 showed a fully pearlitic structure with no grain boundary ferrite. The average distance between cementite lamella in rail MS03 is shorter than that in MS02. The Rockwell C hardness values of MS02 were lower than those of MS03 which is in agreement with the microstructural analysis. As expected, a finer pearlitic structure observed in rail MS03 resulted in a superior tensile and impact properties as compared to MS02. These data indicate that MS03 with a fully pearlitic structure gives a better wear resistance and higher strength than MS02 and, it is anticipated to give a better corrosion and oxidation resistance due to higher chromium content.http://www.satnt.ac.zaam2022Materials Science and Metallurgical Engineerin

‘They care rudely!’: resourcing and relational health system factors that influence retention in care for people living with HIV in Zambia.

Introduction: Despite access to free antiretroviral therapy (ART), many HIV-positive Zambians disengage from HIV care. We sought to understand how Zambian health system ‘hardware’ (tangible components) and ‘software’ (work practices and behaviour) influenced decisions to disengage from care among ‘lost-to-follow-up’ patients traced by a larger study on their current health status. Methods: We purposively selected 12 facilities, from 4 provinces. Indepth interviews were conducted with 69 patients across four categories: engaged in HIV care, disengaged from care, transferred to another facility and next of kin if deceased. We also conducted 24 focus group discussions with 158 lay and professional healthcare workers (HCWs). These data were triangulated against two consecutive days of observation conducted in each facility. We conducted iterative multilevel analysis using inductive and deductive reasoning. Results: Health system ‘hardware’ factors influencing patients’ disengagement included inadequate infrastructure to protect privacy; distance to health facilities which costs patients time and money; and chronic understaffing which increased wait times. Health system ‘software’ factors related to HCWs’ work practices and clinical decisions, including delayed opening times, file mismanagement, drug rationing and inflexibility in visit schedules, increased wait times, number of clinic visits, and frustrated access to care. While patients considered HCWs as ‘mentors’ and trusted sources of information, many also described them as rude, tardy, careless with details and confidentiality, and favouring relatives. Nonetheless, unlike previously reported, many patients preferred ART over alternative treatment (eg, traditional medicine) for its perceived efficacy, cost-free availability and accompanying clinical monitoring. Conclusion: Findings demonstrate the dynamic effect of health system ‘hardware’ and ‘software’ factors on decisions to disengage. Our findings suggest a need for improved: physical resourcing and structuring of HIV services, preservice and inservice HCWs and management training and mentorship programmes to encourage HCWs to provide ‘patient-centered’ care and exercise ‘flexibility’ to meet patients’ varying needs and circumstances

Rethinking retention: mapping interactions between multiple factors that influence long-term engagement in HIV care

Background: Failure to keep people living with HIV engaged in life-long care and treatment has serious implications for individual and population-level health. Nested within a four-province study of HIV care and treatment outcomes, we explored the dynamic role of social and service-related factors influencing retention in HIV care in Zambia. Methods: From a stratified random sample of 31 facilities, eight clinics were selected, one urban and one rural from each province. Across these sites we conducted a total of 69 in-depth interviews, including with patients (including pregnant women) engaged in-care (n = 28), disengaged from care (n = 15), engaged facility transferee (n = 12), and friends/family of deceased patients (n = 14). At the same sites we conducted 24 focus group discussions with a total of 192 lay and professional healthcare workers (HCWs). Two-day observations in each of the eight facilities helped triangulate data on operational context, provider relations and patient-provider interactions. We ordered and analysed data using an adapted version of Ewart's Social Action Theory. Results: Three overarching findings emerged. First, the experience of living with HIV and engaging in HIV care in Zambia is a social, not individual experience, influenced by social and gendered norms and life goals including financial stability, raising family and living stigma-free. Second, patients and their networks act collectively to negotiate and navigate HIV care. Anticipated responses from social network influenced patients' willingness to engage in care, while emotional and material support from those networks influenced individuals' capacity to remain in HIV care. Lastly, health system factors were most influential where they facilitated or undermined peoples' collective approach to health service use. Participants living with HIV reported facilitation of both their initial and continued engagement in care where services involved social networks, such as during couples testing and community outreach. Conversely, service features that were poorly aligned with respondents' social reality (e.g. workplace obligations) hindered long-term engagement. Conclusions: This study moves beyond listing barriers or socio-ecological groupings, to explain how social and health systems interact to produce HIV care outcomes. Our findings challenge the implicit assumption of individual agency underpinning many retention studies to highlight the social nature of illness and healthcare utilization for HIV in Zambia. This understanding of collective action for accessing and remaining in HIV care should underpin future efforts to revise and reform HIV and potentially other chronic service models and systems

Photochemical Degradation of Dissolved Organic Matter and Dissolved Lignin Phenols from the Congo River

Photochemical degradation of Congo River dissolved organic matter (DOM) was investigated to examine the fate of terrigenous DOM derived from tropical ecosystems. Tropical riverine DOM receives greater exposure to solar radiation, particularly in large river plumes discharging directly into the open ocean. Initial Congo River DOM exhibited dissolved organic carbon (DOC) concentration and compositional characteristics typical of organic rich blackwater systems. During a 57 day irradiation experiment, Congo River DOM was shown to be highly photoreactive with a decrease in DOC, chromophoric DOM (CDOM), lignin phenol concentrations (Σ8) and carbon-normalized yields (Λ8), equivalent to losses of ~45, 85–95, \u3e95 and \u3e95% of initial values, respectively, and a +3.1 % enrichment of the δ13C-DOC signature. The loss of Λ8 and enrichment of δ13C-DOC during irradiation was strongly correlated (r = 0.99, p \u3c 0.01) indicating tight coupling between these biomarkers. Furthermore, the loss of CDOM absorbance was correlated to the loss of Λ8 (e.g., a355 versus Λ8; r = 0.98, p \u3c 0.01) and δ13C-DOC (e.g., a355 versus δ13C; r = 0.97, p \u3c 0.01), highlighting the potential of CDOM absorbance measurements for delineating the photochemical degradation of lignin and thus terrigenous DOM. It is apparent that these commonly used measurements for examination of terrigenous DOM in the oceans have a higher rate of photochemical decay than the bulk DOC pool. Further process-based studies are required to determine the selective removal rates of these biomarkers for advancement of our understanding of the fate of this material in the ocean

How might improved estimates of HIV programme outcomes influence practice? A formative study of evidence, dissemination and response

BACKGROUND: While HIV programmes have started millions of persons on life-saving antiretroviral therapy in Africa, longitudinal health information systems are frail and, therefore, data about long-term survival is often inaccurate or unknown to HIV programmes. The \u27Better Information for Health in Zambia\u27 (BetterInfo) Study - a regional sampling-based survey to assess retention and mortality in HIV programmes in Zambia - found both retention and mortality to be higher than prevailing estimates from national surveillance systems. We sought to understand how Zambian health decision-makers at different health system levels would respond to these new data, with a view to informing research translation. METHODS: We interviewed 25 purposefully sampled health decision-makers from community, facility, district, provincial and national levels. During the interviews, we shared retention and mortality estimates from both routine programme surveillance and those generated by the study. Transcripts were analysed for inductive and deductive themes, the latter drawing on Weiss\u27s framework that policy-makers interpret and apply evidence as \u27warning\u27, \u27guidance\u27, \u27reconceptualisation\u27 or \u27mobilisation of support\u27. FINDINGS: All decision-makers found study findings relevant and important. Decision-makers viewed the underestimates of mortality to be a warning about the veracity and informativeness of routine data systems. Decision-makers felt guided by the findings to improve data monitoring and, acknowledging limitations of routine data, utilised episodic patient tracing to support improved data accuracy. Findings catalysed renewed motivation and mobilisation by national level decision-makers for differentiated models of HIV care to improve patient outcomes and also improved data management systems to better capture patient outcomes. Inductive analysis highlighted a programmatic application data interpretation, in which study findings can influence facility and patient-level decision-making, quality of care and routine data management. CONCLUSIONS: New epidemiological data on patient outcomes were widely seen as informative and relevant and can potentially catalyse health system action such as using evaluations to supplement electronic medical record data to improve HIV programmes. Formative evidence suggests that targeting research dissemination at different levels of the health system will elicit different responses. Researchers supporting the translation of evidence to action should leverage all relevant levels of the health system to facilitate both policy and programmatic action

How might improved estimates of HIV programme outcomes influence practice? A formative study of evidence, dissemination and response

Background While HIV programmes have started millions of persons on life-saving antiretroviral therapy in Africa, longitudinal health information systems are frail and, therefore, data about long-term survival is often inaccurate or unknown to HIV programmes. The 'Better Information for Health in Zambia' (BetterInfo) Study - a regional sampling-based survey to assess retention and mortality in HIV programmes in Zambia - found both retention and mortality to be higher than prevailing estimates from national surveillance systems. We sought to understand how Zambian health decision-makers at different health system levels would respond to these new data, with a view to informing research translation. Methods We interviewed 25 purposefully sampled health decision-makers from community, facility, district, provincial and national levels. During the interviews, we shared retention and mortality estimates from both routine programme surveillance and those generated by the study. Transcripts were analysed for inductive and deductive themes, the latter drawing on Weiss's framework that policy-makers interpret and apply evidence as 'warning', 'guidance', 'reconceptualisation' or 'mobilisation of support'. Findings All decision-makers found study findings relevant and important. Decision-makers viewed the underestimates of mortality to be a warning about the veracity and informativeness of routine data systems. Decision-makers felt guided by the findings to improve data monitoring and, acknowledging limitations of routine data, utilised episodic patient tracing to support improved data accuracy. Findings catalysed renewed motivation and mobilisation by national level decision-makers for differentiated models of HIV care to improve patient outcomes and also improved data management systems to better capture patient outcomes. Inductive analysis highlighted a programmatic application data interpretation, in which study findings can influence facility and patient-level decision-making, quality of care and routine data management. Conclusions New epidemiological data on patient outcomes were widely seen as informative and relevant and can potentially catalyse health system action such as using evaluations to supplement electronic medical record data to improve HIV programmes. Formative evidence suggests that targeting research dissemination at different levels of the health system will elicit different responses. Researchers supporting the translation of evidence to action should leverage all relevant levels of the health system to facilitate both policy and programmatic action

Understanding preferences for HIV care and treatment in Zambia: evidence from a discrete choice experiment among patients who have been lost to follow-up

Background: In public health HIV treatment programs in Africa, long-term retention remains a challenge. A number of improvement strategies exist (e.g., bring services closer to home, reduce visit frequency, expand hours of clinic operation, improve provider attitude), but implementers lack data about which to prioritize when resource constraints preclude implementing all. We used a discrete choice experiment (DCE) to quantify preferences for a number of potential clinic improvements to enhance retention. Methods and findings: We sought a random sample of HIV patients who were lost to follow-up (defined as >90 days late for their last scheduled appointment) from treatment facilities in Lusaka Province, Zambia. Among those contacted, we asked patients to choose between 2 hypothetical clinics in which the following 5 attributes of those facilities were varied: waiting time at the clinic (1, 3, or 5 hours), distance from residence to clinic (5, 10, or 20 km), ART supply given at each refill (1, 3, or 5 months), hours of operation (morning only, morning and afternoon, or morning and Saturday), and staff attitude ("rude" or "nice"). We used mixed-effects logistic regression to estimate relative utility (i.e., preference) for each attribute level. We calculated how much additional waiting time or travel distance patients were willing to accept in order to obtain other desired features of care. Between December 9, 2015 and May 31, 2016, we offered the survey to 385 patients, and 280 participated (average age 35; 60% female). Patients exhibited a strong preference for nice as opposed to rude providers (relative utility of 2.66; 95% CI 1.9–3.42; p < 0.001). In a standard willingness to wait or willingness to travel analysis, patients were willing to wait 19 hours more or travel 45 km farther to see nice rather than rude providers. An alternative analysis, in which trade-offs were constrained to values actually posed to patients in the experiment, suggested that patients were willing to accept a facility located 10 km from home (as opposed to 5) that required 5 hours of waiting per visit (as opposed to 1 hour) and that dispensed 3 months of medications (instead of 5) in order to access nice (as opposed to rude) providers. This study was limited by the fact that attributes included in the experiment may not have captured additional important determinants of preference. Conclusions: In this study, patients were willing to expend considerable time and effort as well as accept substantial inconvenience in order to access providers with a nice attitude. In addition to service delivery redesign (e.g., differentiated service delivery models), current improvement strategies should also prioritize improving provider attitude and promoting patient centeredness—an area of limited policy attention to date