Quantification of Total Phenols, Total Flavonoids, Total Anthocyanins and Evaluation of Antioxidant and Antiradical Activities of Detarium Senegalense Extracts from Chad

The aim of the present work is to assess the value of Detarium Senegalense by determining the content of total phenols, total flavonoids and total anthocyanins, and by evaluating the free radical scavenging activity of Detarium Senegalense extracts. For this purpose, sequential extraction using solvents of increasing polarity was essential. The various extracts obtained underwent phytochemical and biochemical analyses. Phytochemical screening revealed the presence of flavonoids, alkaloids, tannins, polyphenols, anthocyanins and steroids/terpenes. Quantitative analysis of total polyphenols, total flavonoids and total anthocyanins yielded the following results: total flavonoids (0.803 ± 0029 mg EQ/100g P for acetone extract of roots and 0.871 ± 0.401 mg EQ/100g P for methanol extract of leaves);total polyphenols (23.298 ± 12.68 mg EAG/100g P for acetone extract of roots and 24.69 ± 0.49 401 mg EAG/100g P for methanol extract of leaves);total monomeric anthocyanins (44.697 ± 0.939 mg EC3G/100g P and 16.699 ± 0.193 mg EC3G/100g P respectively for acetone and methanol extracts of stem bark). DPPH free radical scavenging activity was 1.674 ± 0.023 mg/mL for the acetone extract and 0.934 ± 0.24 mg/mL for the methanol extract of roots. .

Identification of Microorganisms in Poultry Farms in N’djamena and the Border Areas of Hadjer-Lamis and Chari-Baguirmi Chad

Introduction: On the outskirts of Ndjamena, semi-industrial poultry farming and traditional poultry farming are practised informally on almost all poultry farms in Chad. This type of poultry farming is faced with real health problems attributable to a lack of monitoring of the vaccination schedule, inadequate compliance with biosecurity measures and poor application of the Ichikawa rule based on the 5 M’s. Objective: The aim of this article is to identify the microorganisms responsible for contamination of poultry farms in the study area. Method: The study was carried out from 28/04/2022 to 31/01/2023 on the basis of 300 samples taken from feed, drinking water, droppings and scrapings from poultry housing surfaces in the 30 farms that served as a framework for our research. Sampling was of the simple random type, and farms were selected on the basis of the farmers’ consent. The data were recorded on pre-established survey forms. Our study was cross-sectional, descriptive and prospective. Bacteria were isolated using the reference method NF EN ISO 6579 for Salmonella spp. and cultured on the specific medium eosin methylene blue (EMB) for Escherichia coli, Pseudomonas and Citrobacter freundii. Results: The following results emerged from this study: Escherichia coli (5.33%), Pseudomonas (1.33%), Citrobacter freundii (12%) and Salmonella paratyphi (21.68%). Conclusion: Of the 300 samples analysed, 121 (40.33%) were contaminated with pathogens. This high level of contamination is a health problem. The study shows that biosecurity is less satisfactory on the farms visited. Nevertheless, farms with a very satisfactory level of biosafety ensure food safety and variety for the population.

Effect of Acacia albida Leaf Supplementation on Reproductive Parameters and Pre-Weaning Growth of Arabian Lambs

A trial on Acacia albida leaf supplementation on reproductive parameters and pre-weaning growth of Arabian lambs was conducted from September 2020 to May 2021 at the small ruminant station of the Livestock Research Institute for Development (IRED) in N’Djamena, Chad. Forty-eight (48) Arabian sheep (45 non-pregnant females and 3 males for a sex ratio of 1 ram to 15 ewes) with an average weight of 20.3 ± 1.2 kg and aged approximately 2 years were divided into 3 groups of 15 ewes each. The supplemented group received in addition to the dominant forage of the pasture (300 g of Dactyloctenium aegyptium + 300 g of Cenchrus ciliaris + 600 g of Panicum maximum), 400 g and 600 g of Acacia albida leaves/animal/day while the control group received only 300 g of Dactyloctenium aegyptium + 300 g of Cenchrus ciliaris + 600 g of Panicum maximum. From the results of this study, it appears that the ewes that received 400 g of Acacia albida leaves had a significantly higher fertility rate and birth mortality rate (93.03% and 6.25% respectively). Animals in the control group had a significantly higher pre-weaning mortality rate than those receiving Acacia albida leaves as a supplement (16.66% versus 6.66% and 14.28% respectively). The highest weight of the lambs was observed in the ration supplemented with 600 g of Acacia albida leaves (12209.66 g). The total weight gain, as well as the average daily weight gain of the lambs receiving the 600 g Acacia albida leaf ration was significantly higher than those of the other rations. Supplementation with 400 g and 600 g of Acacia albida leaves can be recommended as a protein supplement for breeding ewes and pre-weaned lambs.

Adequacy of Water Use Resources for Drinking and Irrigation, Study Case of Sarh City, Capital of Moyen-Chari Province, CHAD

Our objective is to evaluate adequacy of water for consumption and irrigation. We collected nineteen water samples from 21 to 26, May 2017. Twenty-two physico-chemical and bacteriological parameters were taken into account, electrical conductivity, pH, total hardness, bicarbonate, nitrates, sulfates, chlorides, calcium, sodium, magnesium, potassium, dissolved oxygen and biochemical oxygen demand, chemical oxygen demand, total coliforms, Escherichia Coli, and fecal coliforms. To evaluate water intended for consumption, average values measured parameters were compared to [1] for quality water drinking and we evaluated overall quality of water by means of simplified SEQ-Water grid. Concerning irrigation water, evaluation is based on interpretation of quality parameters of irrigation water that we have calculated;among these parameters we can mention the percentage of sodium, rate of sodium absorption, ratio of magnesium adsorption, residual sodium carbonate. Kelly ratio, Corrosivity ratio and Permeability Index. Results show that surface water is weakly mineralized compared to groundwater and presents a good chemical quality;however, it is slightly altered by presence of organic pollutants. The overall assessment of groundwater quality shows that about 47% of water sampled varies between average quality and very poor quality for consumption. This poor quality is mainly due to presence of nitrates in water, whose content sometimes exceeds the limit authorized by [1]. From a bacteriological point of view, germs of faecal origin such as Total Coliforms, Escherichia Coli and Faecal Coliforms contaminate all groundwater points sampled. They are of poor quality and unfit for human consumption without prior treatment. We also evaluated the quality of water used for irrigation using 6 parameters. The results show that all of our water points are suitable for irrigation, according to the values of CSR and Kelly ratio. The same is true for the permeability index, which shows that all samples fall into class I and II type to indicate their suitability for irrigation purposes. According to [2] all waters are excellent quality for agriculture;and for Richard diagram, 89.5% of waters are generally suitable for irrigation and 10% are generally not suitable for irrigation without prior dilution with low salinity water.

Contamination and Potential Risks of Heavy Metals in the Sediments of the Chari and Logon Rivers in N’Djamena, Chad

The pollution of sediments by inorganic pollutants requires particularly important attention because of their toxicity, their persistence in the environment and their bioaccumulation by animal and plant life. The pollution of sediments by inorganic pollutants requires particularly important attention because of their toxicity, their persistence in the environment and their bioaccumulation by animal and plant living beings. This study focuses on the pollution of sediments of the Chari and Logon rivers in the city of N’Djamena by heavy metals. The objective of this study is to evaluate the degree of contamination, the geo-accumulation index and the degree of the Pollutant Loading Index of some heavy metals (Pb, Cr, Cu, Mn and Cd) and iron in the sediments of the sampled sites. The average concentrations of heavy metals and iron in the sediments are: Pb (10.00 ± 00 μg/Kg to 126 ± 16.52 μg/Kg);Cr VI (0.13 ± 00 mg/Kg to 0.21 ± 00 mg/Kg);Cd (trace);Cu (0.08 ± 0.02 mg/kg to 3.23 ± 0.64 mg/kg);Fe (0.25 ± 0.00 mg/kg to 5.79 ± 0.00 mg/kg);and Mn (0.2 ± 0.00 mg/Kg to 1.1 ± 0.00 mg/Kg);in order of highest to lowest abundance: Fe > Mn > Cd > Cu > Cr VI > Pb for the Logon;Fe > Cu > Mn > Cd > Cr VI > Pb for the Chari and Fe > Mn > Cu > Cd > Cr VI > Pb for the Confluent. The contamination factors for all heavy metals range from no contamination to low contamination for the sediments analyzed. The geo-accumulation indices indicate that the sampled sites are not polluted. The same is true for Er and RI which confirm an absence of ecological risks in the analyzed sediments.

Hydrochemical and Isotopic Characteristics of the Basement Aquifer in the Wadi Fira Area, Eastern Chad

The Wadi-Fira region in eastern Chad is facing dramatic water supply problems, related to the climatic semi-arid context and the reception of refugees from the Darfour, which has increased the local population by 22% these last years. Expansion of agglomerations (temporary new towns), development of agricultural and pastoral practices together with the augmentation of the population have led to dramatic water needs. The basement aquifer of Wadi-Fira constitutes the main source of water supply. However, little is known about this system. Within this context, this work aims at better understanding and identifying hydrogeochemical processes and their relations to groundwater quality within this complex environment, and groundwater recharge mechanisms. 31 groundwater samples were collected at two sites, Am Zoer and Guereda-Iriba, from hand dug wells and deep wells. Major chemical elements were analyzed on all samples and stables isotopes (oxygen-18 and deuterium) on 17 samples. Various methods were used to interpret the hydrochemical data (descriptive and multivariate statistics, Piper and Schoeller diagrams, scatter plots, minerals saturation indices). The stable isotopes were interpreted using conventional IAEA methods. The results permitted to differentiate the laterite reservoir from the deep fractured reservoir. The main process controlling groundwater mineralization is water-rocks interaction and natural minerals dissolution. Ion exchanges, evaporation and anthropogenic activities have also a moderate impact on groundwater quality. Based on isotopes data, it is concluded that groundwater in the basement aquifer is related with modern rainfall. These results provide further insights into this basement aquifer, which is a vital resource for the region of Wadi-Fira.

Diversity and Origin of Indigenous Village Chickens (<i>Gallus gallus</i>) from Chad, Central Africa

In this study we assess the maternal genetic diversity and origin of indigenous village chickens from Chad complementing previous phenotypic and biometric measurements studies. We analysed a 387 bp fragment of the mitochondrial DNA (mtDNA) D-loop region of 181 village chickens from three populations of western Chad (Lake Chad/Hadjer Lamis), central Chad (Guera) and south-west Chad (Pala) and at different poultry markets in N'Djamena. Twenty-five polymorphic sites and 20 haplotypes are identified. Phylogenetic and network analyses group all chicken into a single mtDNA haplogroup D. Comparison with reference sequences shows that this haplogroup is the commonest one observed in chicken and it supports the Indian subcontinent as the maternal center of origin for the village chicken in Chad. Little genetic variation was found within and between populations which is in agreement with a recent and a maternal founding effect for the chicken in the country.

Phytochemical Tests, Assessment of Antioxidant Properties and Isolation of Two Compounds of Ethyl Acetate Extract of Chadian Propolis: Case of Bebotho (Southern Chad)

The present work deals with the research of chemical constituents and evaluation of antioxidant properties of Bebotho propolis. From the ethyl acetate extract, we isolated, using various chromatographic techniques, a mixture of two identical compounds (isomers) indexed PBy4a and PByb. The structures of these compounds were elucidated by means of spectroscopic analysis techniques (MS, IR, 1H-NMR, 13C-NMR, HMBC and HSQC) and by comparison of the spectral data with those described in the literature. Thus, these compounds were identified to a mixture of two chromones namely 5,7-dihydroxy-2-methylchromone-6-C-α-D-glucopyranoside and 5,7-dihydroxy-2-methylchromone-8-C-β-D-glucopyranoside, first reported in propolis. The study of the antiradical power, chelating power and the quantification of phenolic compound of these same extracts, showed interesting properties that propolis extracts have to scavenge free radicals.

Vulnerability Evaluation of Groundwater of N’Djamena City: Contribution of the Parametric Methods GOD and SI

The purpose of this work is to study the vulnerability of the Quaternary aquifer that lies beneath the N’Djamena city Chad. The subsoil of N’Djamena city Chad is made up of a multilayered aquifer in which there are two main aquifers located respectively at a depth of about 10 and 60 m, between the two there is an intermediate aquifer at about 30 m depth. It is this latter water table, generally captured by human-powered pumps, that is the subject of this study. Because of anarchic garbage dumping, wastewater discharge, latrines scattered throughout the city, chemical fertilizers and herbicides used on the banks of Chari River and its tributary the Logone for market gardening, the quality of the water in this aquifer is highly threatened. Moreover, it has been noting that the sources of pollution are constantly increasing in conjunction with the growth of the population, so the knowledge and protection of groundwater are necessary. We have therefore carried out a study of intrinsic vulnerability using two mapping methods (GOD and SI), as mapping is recognized as an effective tool for decision support in the case of safeguarding water resources. The results obtained by the GOD method show that 38% of the study area is covered by high vulnerability, 29% by moderate vulnerability, 21% by low vulnerability and 21% by the very low vulnerability. With the SI method, 54% of the study area is covering by low vulnerability and 46% by the low and moderate vulnerability. The coincidence rate of low nitrate values in groundwater with areas of very low and low vulnerability is 91% and 76% for the GOD and SI methods, respectively. Although these observations validated the different maps obtained, the SI approach seems to be the most adequate for vulnerability tracing in our study area.

The Effects of Degradation Phenomena of the Steel-Concrete Interface in Reinforced Concrete Structures

Reinforced concrete (RC) constructions are the innovation of sustainable constructions replacing masonry constructions. Despite this, the use of concrete and steel to improve the performance of structural members in service is a recurring problem due to the immediate or overtime appearance of cracks. The objective of this work was therefore to assess the damage phenomena of the steel-concrete interface in order to assess the performance of an RC structure. Samples of approximately 30 cm of reinforcement attacked by rust were taken from broken reinforced concrete columns and beams in order to determine the impact of corrosion on high adhesion steel (HA) and therefore on its ability to resist. The experimental results have shown that the corrosion degradation rates of reinforcing bars of different diameters increase as the diameter of the reinforcing bars decreases: 5% for HA12;23.75% for HA8 and 50% for HA6. Using the approach proposed by Mangat and Elgalf on the bearing capacity as a function of the progress of the corrosion phenomenon, these rates made it possible to assess the new fracture limits of corroded HA steels. For HA6 respectively HA8 and HA12, their initial limit resistances will decrease by 4/4, 3/4 and 1/4. Based on the results of this study and in order to guarantee their durability, an RC structure can be dimensioned by taking into account the effects of reinforcement corrosion.

Seroprevalence of Chlamydia trachomatis Infection in Women of Procreate Age in the Mayo-Boneye Department in Chad

Introduction: Chlamydia trachomatis infections constitute a major public health problem, particularly in women. The objective of this study is to identify Chlamydia trachomatis to improve the health of women in the Department of Mayo-Boneye. Methodology: This is a prospective observational study that took place from October to December 2021, including 168 patients with their sociodemographic characteristics. The venous blood of the patients was collected in dry tubes and centrifuged to obtain the serum. The Chlamydia IgG Rapid Test Cassette was used for the detection of antibodies to Chlamydia infection. The Epi Info 7TM software was used to perform the statistical analyses. Results: A total of 168 patients were included in this study. The average age was 26.36 ± 9.21 years, the median was 25.5 years with the extremes of 14 years and 70 years. Among these patients, 46.43% were illiterate, 5.95% and 20.83% were primary and secondary school students, respectively, and 26.79% university students. For marital status, 66.67% were single, 16.67% married, 10.71% divorced and 5.95% widowed. Regarding the profession, 26.79% were traders, 8.93% were employees and 64.29% unemployed. In this study, the 168 patients had performed Chlamydia trachomatis serology among whom 02 (1.19%) were excluded for invalid results and 10.71% presented positive cases. The city of Bongor was the most infected with 61% of cases. Among these patients, 54.22% were linked to risk factors for Chlamydia trachomatis. The most infected age group was between 25 and 35 with a seroprevalence of 5.36% of cases. Conclusion: In this study, Chlamydia trachomatis was positive for 10.71% of diagnosed cases. The most affected age groups are young, sexually active women. The State should emphasize the screening of women, the awareness of students and academics.

Evaluation of two methods of estrus synchronization of cattle in Chad

The results of an artificial insemination experiment carried out in the suburban area of N’Djamena are here reported. Two methods of synchronization (Norgestomet combination/estradiol/PGF2a/PMSG and PGF2a only) were used with Chadian zebu and crossed breeds in 2007 and 2008. Females were inseminated after induction of estrus with semen of French Normand breed. The fertility rate was low with PGF2a (29.41%). The results obtained with the combination of several hormones were better (66.66%). The survival rates of crossbreeds were particularly low, 40% in 2007 and 33.33% in 2008, mainly due to the traditional management of the herd and the lack of technical support. The insemination cost of a cow was 39,550 F CFA in 2007 with PGF2a and 59,200 F CFA in 2008 with the method consisting of combining of four hormones. The cost of producing a calf in those two years was very high, 134,470 F CFA in 2007 and 118,400 F CFA in 2008.

Flow Curves in the Centered Cylindrical Couette Geometry of a Polyethylene Oxide Solution

Polyethylene oxide solutions have a behavioral flexibility that provides researchers with the opportunity to use constitutive law models in a variety of ways for their MRI characterization. Our results obtained in numerical simulation carried out in 2D and 3D for speed profiles of a solution of PEO deployed by the simple method of the cylindrical Couette geometry considering the fluid Newtonian defect, allowed to identify the behavior of fluid complex (rheo-fluidifying threshold fluid). The relevance and the interest of the method are examined by analyzing these results generated by the numerical data obtained, since these profiles depend on the non-Newtonian properties of the fluid which one does not know a priori and which one seeks to measure by postulating first to the power law of Ostwald, then to the truncated power law.

Improvement of the Microalgae Harvest by the “Foaming-Scumming” Function of an Airlift Column

The aim of this research work is to valorize the microalgae grown-up in an Airlift column. The system of fluid circulation and mass transfer is based on the principle of interaction between gas bubbles and a liquid. Thus, this study focuses on the phenomenon of the determination of the vacuum rate, the size and the speed of the bubbles including the optimization of microalgae development within the culture process. In addition, this study tries to understand the close relationship between these phenomena, its environment and the microalgae cell. These studies were conducted on the operation of an Airlift column in aquaculture, mainly in freshwater [1]. However, other researchers [2] are interested in studying saline water. In conclusion, a series of experiments were carried out in order to evaluate the profitability of the Microflotation technique, as a method of separation and concentration in microalgae. These results are very interesting since they reveal that the efficiency of the column, for the foaming-skimming function, is greater by working with less significant air injections, which lead to a reduction in energy cost.

Fuzzy Logic Strategy for Solving an Optimal Control Problem of Therapeutic Hepatitis C Virus Dynamics

This paper aims at the development of an approach integrating the fuzzy logic strategy for a therapeutic hepatitis C virus dynamics optimal control problem. To test the efficiency of this strategy, the authors propose a numerical comparison with the direct method by taking the values of determinant parameters of this disease for people administrating the drugs. The results are in good agreement with experimental data.

Experimental Study of the Behaviour of Lime-Stabilized Clay Soil Blocks by Simple Compression for Wall Construction

This study addresses an experimental approach to stabilizing clay soils with lime.In the preliminary stage and in order to require characteristic properties,untreated clay and sand samples are collected on site and subjected to laboratory identification tests.Then,the so-called“trial and error”process based on production test series is used to mix with water by varying the proportions of the constituents.Using a manual press with a capacity of 5 to 10 tonnes,equipped with a 10×15×28 cm^(3) mould,the free-standing and heavy blocks are produced from the firm mixtures retained.After cures of 7,14 and 28 days,the results of the tests show that the resistance to compression(RC)of the blocks in the dry state increases depending on the lime dosage and the duration of cure.At 6%lime and around 25%sand,the value of the RC of 4,966 MPa after 28 days is higher than the recommended values for load-bearing walls by the Construction Materials Center(CMC)of N’Djamena(2.4 MPa)and CRATerre(4.0 MPa).On the other hand,a 24-h stay of the dry blocks in the water causes the RC to fall from 69%to 72%depending on the lime dosage.However,the absorption coefficient of 2.23 g/cm^(2)·s^(1/2) of blocks with 6%lime is much less than 20 g/cm^(2)·s^(1/2),limit value below which the NFP554 standard qualifies the low capillarity blocks.In short,this stabilization approach makes it possible to obtain blocks resistant to aesthetic appearance,low capillarity and cost to build walls.

Computational Fluid Dynamics Analysis of the Aortic Coarctation

In this work, we first investigated the hemodynamic parameters in the case of a normal aortic arch anatomy and in the case of aortic coarctation anatomy, both generated by using CFX-ICEM-ANSYS simulations. Then, we compared these results with those obtained for a proposed model without and with aortic coarctation, while introducing a real tridimensional magnetic resonance imaging geometry in the simulation process. The conclusion is that our proposed model reproduces, with a high agreement, the real case obtained from imaging data.

Evaluation of Quality Borehole Water Consumed in Public Schools in N’Djamena City(Chad)

In N’Djamena city,majority of population living there is connected to drinking water supply network.However,given untimely water cuts,some schools have chosen to carry out private drilling.Our objective is therefore to assess the quality of water intended for human consumption in these schools,to do this we have carried out a physico-chemical and bacteriological control on a number of water points.Seventeen(17)water points were collected during July 2015 and the physico-chemical parameters analyzed are as follows:pH,EC(Electrical Conductivity),TH(Total Hardness),turbidity,Ca^(2+),Mg^(2+),K^(+),Na^(+),Cl^(-),NO_(3)^(-),HCO_(3)^(-)and SO_(4)^(2-).In addition to this,we looked for possible undesirable germs,indicators of pollution.The results of physico-chemical analyses carried out show that water from most boreholes has good quality with the exception of drilling F7,which has a high conductivity,and drilling F_(3)whose turbidity is also high.Bacteriological analysis shows that all water points contain total germs,the other germs of faecal origin are mainly present in the F9 borehole.

The Environmental Impact of Polycyclic Aromatic Hydrocarbons: Mechanism of Extraction by Bio-Surfactant in a Microwave

In N’Djaména, the use and marketing of certain hydrocarbons does not comply with any standard in force or with regulations provided for this purpose. Their evaporation and unregulated release into the wild significantly affects the ecosystem. The present work consists in developing a method of extraction from sediments polluted by bio surfactant (rhamnolipid) assisted by microwaves. The goal here is to look for the presence of polycyclic aromatic hydrocarbons in polluted sediments. The rhamnolipid used consists of monorhamnolipids and di-rhamnolipids, its emulsion index is 64.66% and is composed of saturated and unsaturated fatty acids having carbon numbers ranging from 12 to 18. We used the microwave micellar extraction process. It was made by keeping the concentration values fixed at 0.15 g/L and the power at 400 W and more. We observed a positive interaction of the rhamnolipid concentration factors and the power of the microwave to obtain the optimal conditions at the time of 50 S, at the concentration of 0.16 g/L and at the power of 443 W for a rate of optimal extraction of 0.91%. Chromatographic analysis by GC-MS of the optimum extracts allowed us to identify twelve (12) C10 to C43 n-alkanes and eight (8) PAHs. It emerges from this analysis that the rhamnolipid extracts seven (7) Polycyclic Aromatic Hydrocarbons in equivalent proportions while the tween 80 extracts only four (4) Polycyclic Aromatic Hydrocarbons with a high proportion (80.02%) of benzo [a] antracene.