Potential use of clay from Burkina Faso as filler in rubber production

raw clay materials deposit in Burkina Faso have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and chemical analysis to evaluate their potentialities to be used in rubber compounds production as filler. The samples are composed principally by aolinite, illite and quartz. The rubber compounds have been done in open two-roll mill at room temperature and tested for cure characteristic (ts5, tc90), ineralogical composition by XRD, microstructure by SEM and mechanical properties (Elongation at break, Tear strength, tensile strength, hardness shore A and modulus). The cure characteristics of the rubber compounds formulated with the sample are feeble than those made with commercial kaolin (control). The mechanical properties are in general, except the longation at break, for the sample lowest than those of control. However the different values obtained with the sample are not far to those obtained with commercial kaolin. The different samples can then be used as filler in rubber production after a pre-treatment to reduce the impurities.Keywords: Raw clay materials, rubber, rheology

Microestrutura e distribuição de Weibull da resistência à ruptura de cerâmicas de argila-talco

International audienceThe mechanical properties of clay-talc ceramics containing 0 to 10 wt% of talc fired at 1100 °C were obtained by flexural measurements. With the average value of flexural strength of 23.1 MPa, the sample with 5 wt% of talc (G5) was the strongest and it had the lowest value of interconnected pore (64%). The scattering of strength values was described with the Weibull distribution model. For all samples, Weibull plots showed either a typical linear behavior or a multi-stage response and the Weibull modulus varied in a large range of 3 to 14, depending on the ceramic type and on the applied load. Interconnections between pores formed a network of possible failures under the stress field, resulting in a change of Weibull plots. Reducing the grain size range and the pore interconnectivity led to a reduced strength distribution. The flaw size range had a unimodal distribution for sample G5 with homogeneous microstructure and correspondingly a Weibull modulus m=9.79. © 2019 Associacao Brasileira de Ceramica. All rights reserved.As propriedades mecânicas das cerâmicas de argila-talco contendo 0 a 10% em massa de talco sinterizadas a 1100 °C foram obtidas por medidas de flexão. Com o valor médio de resistência à flexão de 23,1 MPa, a amostra com 5% de talco (G5) foi a mais forte e apresentou o menor valor de poro interconectado (64%). A dispersão dos valores de resistência foi descrita com o modelo de distribuição de Weibull. Para todas as amostras, os gráficos de Weibull mostraram um comportamento típico linear ou uma resposta de múltiplos estágios e o módulo de Weibull variou em uma ampla faixa de 3 a 14, dependendo do tipo de cerâmica e da carga aplicada. Interconexões entre poros formaram uma rede de possíveis falhas sob o campo de tensão, resultando em uma mudança nos gráficos de Weibull. Reduções da faixa de tamanho dos grãos e da interconectividade dos poros levaram a uma redução na distribuição da resistência. A faixa de tamanho de defeito apresentou uma distribuição unimodal para a amostra G5 com microestrutura homogênea e correspondentemente um módulo de Weibull m=9,79

Microstructure and Weibull distribution of rupture strength of clay-talc ceramics

International audienceThe mechanical properties of clay-talc ceramics containing 0 to 10 wt% of talc fired at 1100 °C were obtained by flexural measurements. With the average value of flexural strength of 23.1 MPa, the sample with 5 wt% of talc (G5) was the strongest and it had the lowest value of interconnected pore (64%). The scattering of strength values was described with the Weibull distribution model. For all samples, Weibull plots showed either a typical linear behavior or a multi-stage response and the Weibull modulus varied in a large range of 3 to 14, depending on the ceramic type and on the applied load. Interconnections between pores formed a network of possible failures under the stress field, resulting in a change of Weibull plots. Reducing the grain size range and the pore interconnectivity led to a reduced strength distribution. The flaw size range had a unimodal distribution for sample G5 with homogeneous microstructure and correspondingly a Weibull modulus m=9.79. © 2019 Associacao Brasileira de Ceramica. All rights reserved.As propriedades mecânicas das cerâmicas de argila-talco contendo 0 a 10% em massa de talco sinterizadas a 1100 °C foram obtidas por medidas de flexão. Com o valor médio de resistência à flexão de 23,1 MPa, a amostra com 5% de talco (G5) foi a mais forte e apresentou o menor valor de poro interconectado (64%). A dispersão dos valores de resistência foi descrita com o modelo de distribuição de Weibull. Para todas as amostras, os gráficos de Weibull mostraram um comportamento típico linear ou uma resposta de múltiplos estágios e o módulo de Weibull variou em uma ampla faixa de 3 a 14, dependendo do tipo de cerâmica e da carga aplicada. Interconexões entre poros formaram uma rede de possíveis falhas sob o campo de tensão, resultando em uma mudança nos gráficos de Weibull. Reduções da faixa de tamanho dos grãos e da interconectividade dos poros levaram a uma redução na distribuição da resistência. A faixa de tamanho de defeito apresentou uma distribuição unimodal para a amostra G5 com microestrutura homogênea e correspondentemente um módulo de Weibull m=9,79

Formulation de briques réfractaires en argile : influence de la nature de la chamotte et de la teneur en alumine de l'argile

National audienc

Residual risk of hepatitis B virus transmission through blood donations in Burkina Faso screened with rapid diagnostic tests

Abstract Background and Aims hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) represent the major transfusion–transmissible pathogens worldwide. The risk of transmission is relatively high in African countries, mainly due to unreliable screening methods of blood donations. In Burkina Faso, predonation screening using rapid diagnostic tests (RDTs) is widespread, raising the major question of the transfusion safety in the country. The objective of this study was to assess the risk of transmission of HBV, HCV, and HIV through blood transfusion in the context of the use of RDTs for screening of the blood donations. Methods In this cross‐sectional study, a total of 417 serum samples obtained from blood donors tested negative for HBsAg, anti‐HCV, and anti‐HIV using RDTs were retested for the same markers using chemiluminescent immunologic assays. Total antibodies to HBV core (anti‐HBc) were tested on randomly selected samples. HBV‐DNA and HCV‐RNA viral loads (VLs) were quantified on HBsAg and anti‐HCV positive samples, respectively. To assess possible occult hepatitis B infection (OBI), HBV‐DNA‐VL was quantified on 313 randomly selected HBsAg‐negative samples. Results HBsAg and anti‐HCV were found respectively in 6 (6/417; 1.4%) and 11 (11/417; 2.6%) samples. No samples were reactive for anti‐HIV. Total anti‐HBc were detected in 217 out of the 319 randomly selected samples (217/319; 68.02%). HBV‐DNA was detected in four (4/313; 1.27%) samples, including two (2/6; 33.33%) of the six HBsAg positive samples and two (2/313; 0.6%) of the HBsAg‐negative samples, suggesting two cases of occult HBV infection. All anti‐HCV antibody‐positive samples were HCV‐RNA negative. Conclusion This study shows that RDTs are not sufficiently sensitive for the screening of blood donations. Our results highlight the urgent need to think about the extension of sensitive immunological tests in all blood transfusion centers and also the implementation of nucleic acid amplification techniques

Malaria positivity following a single oral dose of azithromycin among children in Burkina Faso: a randomized controlled trial.

BackgroundAzithromycin is a broad-spectrum antibiotic that has moderate antimalarial activity and has been shown to reduce all-cause mortality when biannually administered to children under five in high mortality settings in sub-Saharan Africa. One potential mechanism for this observed reduction in mortality is via a reduction in malaria transmission.MethodsWe evaluated whether a single oral dose of azithromycin reduces malaria positivity by rapid diagnostic test (RDT). We conducted an individually randomized placebo-controlled trial in Burkina Faso during the high malaria transmission season in August 2020. Children aged 8 days to 59 months old were randomized to a single oral dose of azithromycin (20 mg/kg) or matching placebo. At baseline and 14 days following treatment, we administered a rapid diagnostic test (RDT) to detect Plasmodium falciparum and measured tympanic temperature for all children. Caregiver-reported adverse events and clinic visits were recorded at the day 14 visit.ResultsWe enrolled 449 children with 221 randomized to azithromycin and 228 to placebo. The median age was 32 months and 48% were female. A total of 8% of children had a positive RDT for malaria at baseline and 11% had a fever (tympanic temperature ≥ 37.5 °C). In the azithromycin arm, 8% of children had a positive RDT for malaria at 14 days compared to 7% in the placebo arm (P = 0.65). Fifteen percent of children in the azithromycin arm had a fever ≥ 37.5 °C compared to 21% in the placebo arm (P = 0.12). Caregivers of children in the azithromycin group had lower odds of reporting fever as an adverse event compared to children in the placebo group (OR 0.41, 95% CI 0.18-0.96, P = 0.04). Caregiver-reported clinic visits were uncommon, and there were no observed differences between arms (P = 0.32).ConclusionsWe did not find evidence that a single oral dose of azithromycin reduced malaria positivity during the high transmission season. Caregiver-reported fever occurred less often in children receiving azithromycin compared to placebo, indicating that azithromycin may have some effect on non-malarial infections. Trial registration Clinicaltrials.gov NCT04315272, registered 19/03/2020