Impact of the Degrading Toxicity of Metallic Trace Elements on the Flora and Fauna of the Matete River in Kinshasa

This work presents the results for which the general objective pursued in this study is to assess the impact of the degrading toxicity of metallic trace elements on the flora and fauna of the Matete river in Kinshasa. This evaluation was studied through the understanding of the accumulative power of species of flora and fauna in this same ecosystem with metallic elements. In particular: Pistia stratiotes (manganese): 10.7 ± 1.1 and 236.4 × 101 ± 248.8 mg / kg, iron: from 187.5 × 101 ± 61.9 and 500.0 × 101 ± 0, 1 mg / kg, potassium: between 314.8 ± 12.1 and 119.0 × 103 ± 6981.1 mg / kg, calcium: <10 ± <0.3 and 252200 ± 1892.8 mg / kg, cobalt: <3.0 ± <0.2, nickel: <0.5 ± <0.1 and 20.6 ± 0.5 mg / kg, zinc: 1.9 ± 0.0 and 98.7 × 101 ± 0.0 mg / kg, copper: <0.5 ± <0.1 and 79.4 ± 1.2 mg / kg, aluminum: 56.3 × 101 ± 53.1 and 5229.0 × 101 ± 583, 8 mg / kg, chromium: <1.0 ± <0.1 mg / kg and 21.6 ± 4.0 mg / kg, cadmium: 2.8 ± 0.3 and 25.6 ± 0.4 mg / kg, lead: 0.5 ± 0.4 and 86.7 ± 5.5 mg / kg and for Lemna minor (manganese): 5.10 ± 0.1 and 5.80 ± 0.3 mg / kg, iron: 49.9 × 101 ± 18.8 and 6784.0 × 101 ± 709.5 mg / kg, potassium: 113.8 ± 4.4 and 2712.0 × 101 ± 98.8 mg / kg, calcium: <10 ± <0.1 and 97830 ± 2073.9 mg / kg, cobalt: <3.0 ± <0.2 mg / kg, nickel: 0.001 ± 0.00 and 0.004 ± 0.00 mg / kg, zinc : 3.12 ± 0.17 and 4.00 ± 0.82 mg / kg, copper: 0.001 ± 0.0001 and 0.006 ± 0.0004 mg / kg, aluminum: 0.02 ± 0.00 mg / kg and 0.15 ± 0.06 mg / kg, chromium: 0.001 ± 0.0001 and 0.003 ± 0.0002 mg / kg, cadmium: 0.0004 ± 0.00002 and 0.001 ± 0.00003 mg / kg, lead: 0.001 ± 0.00 and 0.004 ± 0.0002 mg / kg. On the other hand, Oreochromis niloticus (Calcium): <0.1 × 102 ± 0.3 and 25 220.0 × 101 ± 48094.1mg / kg, Iron: 10350.7 × 101 ± 5131.7 and 102158.0 × 101 ± 27182.7,Manganese: 1.815 × 101 ± 0.931mg / kg and 7.945 × 101 ± 2.131 mg / kg, Cobalt: <6.0 ± <0.0 mg / kg, Nickel: <0.501 ± <0.049 mg / kg and 61.503 ± 1.302 mg / kg, Zinc: <0.736 ± 0.015 mg / kg and 42.923 × 101 ± 3.176 mg / kg, Copper: 1.902 ± 0.007 mg / kg and 35.302 ± 0.247 mg / kg, Aluminum: 1.414 × 103 ± 70.464mg / kg and 9.493 × 103 ± 147.214 mg / kg, Chromium: <1.0001 ± <0.0408 and <1.0003 ± <0.0105, Cadmium: 0.2002 ± 0.0718 mg / kg and 19.0001 ± 0.8981mg / kg and Lead: <1, 0002 ± <0.0051 mg / kg and 3.9004 ± 0.0895 mg / kg of dry matter. One of the serious causes of their persistence is their biomagnification in the food chain. This is why the response of  Pistia stratiotes, water lettuce and Lemna minor from the nine sampling sites of the Matete river to large and / or low concentrations of metallic elements is reflected either by an inhibition of photosynthetic processes (antagonism and effect synergistic) and the instinct of certain species. However, this ecosystem offers an ecological niche low in dissolved oxygen and a nutrient-poor and toxic diet for the species that live there. In this regard, the flora of the Matete river accumulates the metallic elements in a significant way and according to the diversity of the environments and the size of the species

Numerical and experimental study of an air-soil heat exchanger for cooling habitat in Sahelian zone: case of Ouagadougou

The use of air-soil heat exchangers for the cooling home has developed considerably in recent years. In this work, we have leaded the numerical study of an air-soil heat exchanger by using a nodal approach. We have also presented our experimental prototype implemented in Ouagadougou. This study has allowed determining the evolution of air temperature along the exchanger and also validating our numerical results with those of the literature and the experiment

Biodiversity of the phosphate solubilizing microorganisms (PSMs) population from the rice rhizosphere soils of the two agro-ecological zones of Cameroon

The plant rhizosphere microorganisms having the phosphate solubilizing capacity can convert the insoluble soil organic and inorganic phosphates into a soluble form and make the phosphorus (P) available to the plant. With the objective of evaluating the phosphate solubilizing microorganism populations under the rice rhizosphere, soils samples were collected in three locations of two agro ecological zones of Cameroon and analyzed for their PSMs diversity. Isolation of microorganisms was made on non selective nutrient agar plates and the phosphate solubilizing activity of isolates was tested on National Botanical Research Institute’s Phosphate growth medium (NBRIP) amended with sparingly soluble rock phosphates of different origins. The morphological description of isolates allowed evaluating the phosphate solubilizing microorganism’s diversity under the rice rhizospheric soil. The most probable number of PSMs ranged between 22 and 53% with an average of 48%, 52.80% and 22.44% for Nkolbisson, Nyokon and Santchou respectively. The 65 isolates obtained from all locations were distributed in four diverse groups. The index of solubilization ranged between 2.70 and 7.24 depending on isolate. From a total of 65 isolates obtained from the three sampling sites, 46 were phosphate solubilizing isolates among which: 20 were of low solubilization, 16 of medium and 10 of high solubilization. This is the first work reporting phosphate solubilizing microorganisms on rice rhizosphere in Cameroon. However, the selection of phosphate solubilizing microorganisms as possible inoculation tools for phosphate-deficient soils should focus on the integral interpretation of laboratory assays, greenhouse experiments as well as field trials.© 2015 International Formulae Group. All rights reserved.Keywords: Diversity, index of solubilization, isolates, rice, rock phosphate

Constraint algorithm for k-presymplectic Hamiltonian systems. Application to singular field theories

The k-symplectic formulation of field theories is especially simple, since only tangent and cotangent bundles are needed in its description. Its defining elements show a close relationship with those in the symplectic formulation of mechanics. It will be shown that this relationship also stands in the presymplectic case. In a natural way, one can mimick the presymplectic constraint algorithm to obtain a constraint algorithm that can be applied to $k$-presymplectic field theory, and more particularly to the Lagrangian and Hamiltonian formulations of field theories defined by a singular Lagrangian, as well as to the unified Lagrangian-Hamiltonian formalism (Skinner--Rusk formalism) for k-presymplectic field theory. Two examples of application of the algorithm are also analyzed.Comment: 22 p

Deformations of duality-symmetric theories

We prove that a sum of free non-covariant duality-symmetric actions does not allow consistent, continuous and local self-interactions that deform the gauge transformations. For instance, non-Abelian deformations are not allowed, even in 4 dimensions where Yang-Mills type interactions of 1-forms are allowed in the non-manifestly duality-symmetric formulation. This suggests that non-Abelian duality should require to leave the standard formalism of perturbative local field theories. The analyticity of self-interactions for a single duality-symmetric gauge field in four dimensions is also analyzed.Comment: 35 pages, typo corrections and one reference added, submitted to Nucl. Phy

High Prevalence of Both Humoral and Cellular Immunity to Zaire ebolavirus among Rural Populations in Gabon

To better understand Zaire ebolavirus (ZEBOV) circulation and transmission to humans, we conducted a large serological survey of rural populations in Gabon, a country characterized by both epidemic and non epidemic regions. The survey lasted three years and covered 4,349 individuals from 220 randomly selected villages, representing 10.7% of all villages in Gabon. Using a sensitive and specific ELISA method, we found a ZEBOV-specific IgG seroprevalence of 15.3% overall, the highest ever reported. The seroprevalence rate was significantly higher in forested areas (19.4%) than in other ecosystems, namely grassland (12.4%), savannah (10.5%), and lakeland (2.7%). No other risk factors for seropositivity were found. The specificity of anti-ZEBOV IgG was confirmed by Western blot in 138 individuals, and CD8 T cells from seven IgG+ individuals were shown to produce IFN-γ after ZEBOV stimulation. Together, these findings show that a large fraction of the human population living in forested areas of Gabon has both humoral and cellular immunity to ZEBOV. In the absence of identified risk factors, the high prevalence of “immune” persons suggests a common source of human exposure such as fruits contaminated by bat saliva. These findings provide significant new insights into ZEBOV circulation and human exposure, and raise important questions as to the human pathogenicity of ZEBOV and the existence of natural protective immunization

Singular lagrangians: some geometric structures along the Legendre map

New geometric structures that relate the lagrangian and hamiltonian formalisms defined upon a singular lagrangian are presented. Several vector fields are constructed in velocity space that give new and precise answers to several topics like the projectability of a vector field to a hamiltonian vector field, the computation of the kernel of the presymplectic form of lagrangian formalism, the construction of the lagrangian dynamical vector fields, and the characterisation of dynamical symmetries.Comment: 27 pages; minor changes, a reference update

Bypass and hyperbole in soil science:A perspective from the next generation of soil scientists

International audienceWe, the co‐authors of this letter, are an international group of soil scientists at early career stages, from PhD students to postdoctoral researchers, lecturers, and research fellows with permanent positions. Here, we present our collective musings on soil research challenges and opportunities and, in particular, the points raised by Philippe Baveye (Baveye, 2020a, 2020b) and Johan Bouma (Bouma, 2020) on bypass and hyperbole in soil science. Raising awareness about these issues is a first and necessary step. To this end, we would like to thank Philippe Baveye and Johan Bouma for initiating this debate.......

First serological evidence of West Nile virus in human rural populations of Gabon

To investigate West Nile virus (WNV) circulation in rural populations in Gabon, we undertook a large serological survey focusing on human rural populations, using two different ELISA assays. A sample was considered positive when it reacted in both tests. A total of 2320 villagers from 115 villages were interviewed and sampled. Surprisingly, the WNV-specific IgG prevalence was high overall (27.2%) and varied according to the ecosystem: 23.7% in forested regions, 21.8% in savanna, and 64.9% in the lakes region. The WNV-specific IgG prevalence rate was 30% in males and 24.6% in females, and increased with age. Although serological cross-reactions between flaviviruses are likely and may be frequent, these findings strongly suggest that WNV is widespread in Gabon. The difference in WNV prevalence among ecosystems suggests preferential circulation in the lakes region. The linear increase with age suggests continuous exposure of Gabonese populations to WNV. Further investigations are needed to determine the WNV cycle and transmission patterns in Gabon

Neopterin is a cerebrospinal fluid marker for treatment outcome evaluation in patients affected by Trypanosoma brucei gambiense sleeping sickness.

BACKGROUND: Post-therapeutic follow-up is essential to confirm cure and to detect early treatment failures in patients affected by sleeping sickness (HAT). Current methods, based on finding of parasites in blood and cerebrospinal fluid (CSF) and counting of white blood cells (WBC) in CSF, are imperfect. New markers for treatment outcome evaluation are needed. We hypothesized that alternative CSF markers, able to diagnose the meningo-encephalitic stage of the disease, could also be useful for the evaluation of treatment outcome. METHODOLOGY/PRINCIPAL FINDINGS: Cerebrospinal fluid from patients affected by Trypanosoma brucei gambiense HAT and followed for two years after treatment was investigated. The population comprised stage 2 (S2) patients either cured or experiencing treatment failure during the follow-up. IgM, neopterin, B2MG, MMP-9, ICAM-1, VCAM-1, CXCL10 and CXCL13 were first screened on a small number of HAT patients (n = 97). Neopterin and CXCL13 showed the highest accuracy in discriminating between S2 cured and S2 relapsed patients (AUC 99% and 94%, respectively). When verified on a larger cohort (n = 242), neopterin resulted to be the most efficient predictor of outcome. High levels of this molecule before treatment were already associated with an increased risk of treatment failure. At six months after treatment, neopterin discriminated between cured and relapsed S2 patients with 87% specificity and 92% sensitivity, showing a higher accuracy than white blood cell numbers. CONCLUSIONS/SIGNIFICANCE: In the present study, neopterin was highlighted as a useful marker for the evaluation of the post-therapeutic outcome in patients suffering from sleeping sickness. Detectable levels of this marker in the CSF have the potential to shorten the follow-up for HAT patients to six months after the end of the treatment