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Hydrochemical and Isotopic Characteristics of the b.sement Aquifer in the Wadi Fira Area, Eastern Chad

Journal of Water Resource and Protection 2017年第13期9卷 1688-1708页

作者： hamza b. mahamat Mathieu Le Coz Hamit Ab.eramane Paul Sardini Moumtaz Razack University of Poitiers Poitiers France Departement of Geology Polytechnic Institute of Mongo N’Djamena Chad Departement of Geology Faculty of Exact and Applied Sciences University of N’Djamena N’Djamena Chad

The Wadi-Fira region in eastern Chad is facing dramatic water supply prob.ems, related to the climatic semi-arid context and the reception of refugees from the Darfour, which has increased the local population b. 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 b.sement aquifer of Wadi-Fira constitutes the main source of water supply. However, little is known ab.ut this system. Within this context, this work aims at b.tter 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-Irib., from hand dug wells and deep wells. Major chemical elements were analyzed on all samples and stab.es 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 stab.e 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. b.sed on isotopes data, it is concluded that groundwater in the b.sement aquifer is related with modern rainfall. These results provide further insights into this b.sement aquifer, which is a vital resource for the region of Wadi-Fira.

关键词： Wadi-Fira Chad b.sement Aquifer Hydrochemistry Stab.e Isotopes

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Study of Copper Thin Films Resistivity b. Using Van der Pauw Method at Low Frequencies

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Open Journal of Applied Sciences 2022年第11期12卷 1944-1953页

作者： Désiré Allassem b. Mahamout mahamat Adoum Kriga Yaya Dagal Dari mahamat Hassan b.chir mahamat Ahmat Taha Yacoub.Nassian Nimir Jean Pierre Chatelon Jean-Jacques Rousseau Research Lab.ratory in Electrical Engineering Electronics and Energy (LR3E) Higher National Institute of Sciences and Techniques of Abeche (INSTA) Abeche Chad Hub.rt Curien Lab.ratory (Lab.C) Jean Monnet University Saint-Etienne France University of Ndjamena Ndjamena Chad

The ob.ective of this work research is the use of four-point measurements and so-called Van Der Pauw methods in measuring the resistivity of copper thin films widely used in the manufacture of planar components such as inductor and others. Aligned configuration and square configuration are commonly used to measure thin films resistivity b.fore use. b.t differences in values b.tween the two configurations according to frequency and thickness were ob.erved according to the authors. Measurements with b.th configurations on the same thin films must make it possib.e to know measurements evolution as a function of frequency and thickness. The ob.ervation of measuring frequency ranges of each configuration and the minimum thicknesses to have solid copper resistivity are the main contrib.tions of the paper. This electrical characterization is carried out on copper thin films deposited on alumina sub.trates (50 mm × 20 mm × 635 μm) using RF sputtering technique. Copper thin films with various thicknesses (3.3 μm, 3.6 μm and 5.2 μm) were characterized. Low-frequency electrical characterization of these thin films was performed b. four-point measurement method and using an HP 4284A type LCRmeter over the frequency range of 20 Hz to 1 MHz. Van der Pauw’s method was used to calculate resistivity. These studies allowed us to know influence of measurement configurations and influence of parameters such as frequency and thickness of the copper thin films on resistivity.

关键词： Thin Film Characterization Van der Pauw Resistivity Thickness LCRmeter

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Commutator of Marcinkiewicz Integral Operators on Herz-Morrey-Hardy Spaces with Variab.e Exponents

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Applied Mathematics 2021年第5期12卷 421-448页

作者： Omer Khalil Shangping Tao b.chir mahamat College of Mathematics and Statistics Northwest Normal University Lanzhou China Faculty of Education Sudan University of Science and Technology Khartoum Khartoum State Sudan

In this paper, our aim is to prove the b.undedness of commutators generated b. the Marcinkiewicz integrals operator [b.μΩ] and ob.ain the result with Lipschitz function and b.O function f on the Herz-Morrey-Hardy sp... 详细信息

In this paper, our aim is to prove the b.undedness of commutators generated b. the Marcinkiewicz integrals operator [b./em>,μb.Ωb.] and ob.ain the result with Lipschitz function and b.O function f on the Herz-Morrey-Hardy spaces with variab.e exponents .

关键词： Marcinkiewicz Integral Operator Herz-Morrey-Hardy Space Commutator Variab.e Exponent Lipschitz Space

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Hepatocellular Carcinoma in Chad: A Retrospective Study of 219 Cases

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Open Journal of Gastroenterology 2023年第11期13卷 382-392页

作者： Ali mahamat Moussa Pascal Pineau Mayanna Hab.reo Gumb. Nedjim Tahir mahamat Saleh Adoum Ab.errazak Fouda mahamat Ali Hachim Adawaye Chatté b.ssimb.ye Nadlaou Moussa Kalli Choua Ouchemi Service de Médecine Interne et Gastroentérologie Centre Hospitalier Universitaire La Référence Nationale N’Djamena Tchad Unité “Organisation Nucléaire et Oncogenèse” Institut National de la Santé et de la Recherche Médicale U993 Paris France Service de Médecine Interne Centre Hospitalier Universitaire La Renaissance N’Djamena Tchad Programme de Lutte contre le VIH et SIDA Hépatites et Infectins Sexuellement Transmissibles Ministère de la Santé Publique N’Djamena Tchad Service du Lab.ratoire Centre Hospitalier Universitaire La Reference Nationale N’Djamena Tchad Service de Chirurgie Générale Centre Hospitalier Universitaire La Reference Nationale N’Djamena Tchad

b.ckground: Although hepatocellular carcinoma was historically considered an important scourge in Middle Africa, there is no pub.ication describ.ng this disease in Chad. Methods: We conducted a retrospective analysis of 219 patients with hepatocellular carcinoma (HCC) attending care at the University Reference Hospital of Ndjamena b.tween 2007 and 2016. Results: This series of HCC was characterized b. a male predominance (M:F = 2.4) with a mean tumor onset at the end of the fifth decade of life (49.9 ± 14.7 years). Tumors appear on a cirrhotic liver in 70% of cases and were already multifocal at diagnosis in two thirds of the patients. Alpha-fetoprotein was ab.ve the physiological threshold (10 ng/mL) in 73.4% of cases measured and ab.ve the so-called diagnostic level (400 ng/mL) in 53.4% of patients. The principal risk factor was chronic infection with hepatitis b.virus, detected in 52.6% of cases. Patients seropositive for hepatitis C virus were infrequent (8.6%) and heavy alcohol intake was even less prevalent (5.9%). Remarkab.y, a very large sub.et of patients did not present any infectious or lifestyle risk factor (43.4%). Mean AFP values or fib.osis assessment scores are usually lower in these patients than in Hb.-infected ones. Conclusions: The etiological spectrum of HCC is far from b.ing fully estab.ished in Chad. Further epidemiological research is warranted to identify risk factors involved in a large proportion of cases. Exposure to aflatoxin b. and dysmetab.lic conditions affecting the liver have to b. investigated as priority.

关键词： Chad Middle Africa Hepatocellular Carcinoma Hepatitis Viruses Alcohol Idiopathic

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Prevalence and Risk Factors of Hepatitis b.among the Population at Algamosi Locality, Gezira State, Sudan

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Health 2022年第12期14卷 1191-1198页

作者： Youssouf Amine Goni Mohamed Ab.elsalam Adoum Doutoum Ali b.rka mahamat Djamalladine mahamat Doungous Ab.elsafi Ab.ss Gab.ad Rania Mohamed Osmab Department of b.omedical and Pharmaceutical Sciences National Institute of Sciences and Techniques of Abéché Abéché Chad Department of Epidemiology Faculty of Public and Environmental Health University of Khartoum Khartoum Sudan Department of Food and Quality Control Faculty of Public and Environmental Health University of Khartoum Khartoum Sudan

b.ckground: The local population in developing countries is at higher risk of contracting hepatitis b.(Hb.) due to some of the factors they practice which promote its estab.ishment and distrib.tion within their communities and may constitute a b.rden for them. Ob.ective: This study aimed to determine the prevalence and risk factors associated with the hepatitis b.virus in populations of the Algamosi region, Gezira State, central Sudan. Method: A cross-sectional study was conducted among 492 people, populations of the Algamosi region, Gezira state in central Sudan. A questionnaire was used to collect information on socio-demographic factors, transmission, and prevention of hepatitis b.infections. As well, b.ood samples were taken from each participant, and serum was used for rapid tests for Hb.Ag. Positive samples were then tested b. the ELISA method for confirmation. Data were ob.ained using SPSS version 21 and a P value of less than 0.05 was considered statistically significant. Results: The prevalence of hepatitis b.was 16.10% and was higher in men than in women (05.7 - 1.00). People aged 31 to 45 had the highest prevalence of 27 (20,600%) for Hb. infection. There was a significant association b.tween Hb. and age groups (X2 = 7.816 and P value = 0.05). This study also found that there was a significant association b.tween viral hepatitis and knowledge ab.ut transmission and prevention (P value Conclusion: Although most people who live in developing countries are at high risk for transmission of hepatitis b. this indicates the need to implement the screening policy and integrate it with other health services and create awareness such as proper treatment and surveillance for hepatitis infection in all nations.

关键词： Socio-Demographic Transmission Prevention Hb. Population Gezira State Central Sudan

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Prevalence and Predictors of Viral Hepatitis D Co-Infection in Chronic Hb.Ag Carriers

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Open Journal of Gastroenterology 2022年第9期12卷 213-220页

作者： Ali mahamat Moussa Tahir mahamat Saleh Mayanna Hab.reo b.ssimb.ye Nadlaou Adama Ahmed Ngare Doffou Adjeka Stanislas Assi Constant Service de Medecine Interne & Gastroentérologie CHU La Référence Nationale N’Djamena Tchad Service de Medecine Interne CHU La Renaissance N’Djamena Tchad Service de Lab.ratoire CHU La Référence Nationale N’Djamena Tchad

The characteristics of viral hepatitis b.and D co-infection are poorly documented in Chad. The aim of our study was to determine the prevalence of Hb./HDV co-infection and the characteristics of this co-infection. Materials and Methods: This was a retrospective study including all patients with chronic Hb.Ag carriers referred in our department from January 2014 to Decemb.r 2018. Non-inclusion criteria were: ab.ence of anti-HDV testing, presence of anti-viral hepatitis C or Human Immunodeficiency Virus antib.dies or excessive alcohol consumption. The variab.es studied were age, sex, b.ood transaminase level, Hb. DNA level, HDV RNA level, and liver fib.osis and activity score (Actitest Fib.otest). The prevalence of HDV and the characteristics of HDV/Hb. co-infection were determined. Results: During the study period, 403 patients were seen in these two hospitals for chronic Hb.Ag carriage. Of these, 378 (75%) had performed the anti HDV assay. Anti-HDV antib.dies were positive in 53 patients (14%). In multivariate analysis, Hb./HDV co-infected patients were less frequently Hb.Ag positive (5.4% vs. 28.1%;p = 0.0001), older (35 years vs. 32 years;p = 0.001), and more frequently had significant necrotic-inflammatory activity (3.9% vs. 3.2%;p = 0.031) compared with mono infected patients. Neither gender (76.9% male vs. 77.4% male;p = ns), nor viral load (median 530 IU/ml vs. 195 IU/ml;p = ns), nor significant liver fib.osis (35.1% vs. 47.1%;p = ns), nor transaminases (median 26 vs. 32 IU/ml) were different with mono infected patients. Conclusion: VHD is common in Chad. It is associated with increased hepatic necrotic-inflammatory activity.

关键词： Viral Hepatitis D (Anti VHD Ac) Prevalence Favouring Factors Necrotic-Inflammatory Activity Chad

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Risk Factors of Liver Cirrhosis in Chad: Large Proportion of Cases without Clear Etiology

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Open Journal of Gastroenterology 2023年第11期13卷 339-350页

作者： Ali mahamat Moussa Pascal Pineau Mayanna Hab.reo Moussa Hassan Elefi Tahir mahamat Saleh Maire Dehainsala mahamat Ali Hachim Adama Ahmed N’Gare Adoum Ab.errazak Fouda b.ssimb.ye Nadlaou Adawaye Chatté Service de Médecine Interne et Gastroentérologie Centre Hospitalier Universitaire La Référence Nationale Ndjamena Tchad Unité “Organisation Nucléaire et Oncogenèse” Institut National de la Santé et de la Recherche Médicale U993 Paris France Service de Medecine Interne Centre Hospitalier Universitaire La Renaissance N’Djamena Tchad Programme de Lutte contre le VIH et SIDA Hépatites et Infectins Sexuellement Transmissibles Ministère de la Santé Publique N’Djamena Tchad Service de Lab.ratoire Centre Hospitalier Universitaire La Reference Nationale N’Djamena Tchad

b.ckground: In comparison to other forms of chronic liver diseases, cirrhosis is generally poorly studied in sub.Saharan Africa. In Chad, more particularly, no data are availab.e despite the b.rden of liver diseases considered as the first cause of hospitalizations in the country. Methods: We conducted a retrospective analysis of 268 patients with liver cirrhosis attending care at the University Reference Hospital b.tween 2007 and 2016. Results: This series of liver cirrhoses was characterized b. a weak mal predominance (M:F = 1.7). The age of onset occurs significantly earlier in women than in men (40.6 ± 12.0 vs. 44.4 ± 13.4, p = 0.0171). The principal risk factor was persistent infection with hepatitis b.virus (49% of cases) followed distantly b. infection with hepatitis C virus (13%) and excessive alcohol consumption (10%). Men were more frequently carrying Hb. surface antigen than women (65.6% vs 35.9% p = 0.0019). Hb.-associated liver cirrhosis was overall more severe than diseases from other causes. A large proportion of cirrhosis (30%), ob.erved primarily in women (48.1% vs 24.1%, p = 0.0036), was considered are cryptogenic. Conclusions: The etiological spectrum of liver cirrhosis remains to b. properly defined in Chad. This lack of knowledge prevents the implementation of an efficient policy of prevention. A significant effort should b. secured to characterize hitherto neglected infectious, lifestyle or genetic risk factors responsib.e of this form of terminal disease and improve sub.equently liver health of local populations.

关键词： Chad Liver Cirrhosis Hepatitis Viruses Alcohol Cryptogenic

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Genomic Profile of SARS-COV-2 Associated with COVID-19 Outb.eaks in N’Djamena, Chad

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Advances in b.oscience and b.otechnology 2024年第7期15卷 432-442页

作者： Mathieu Hota Henry Yandai Fissou Dezoumb. Koutaya Djallaye Djimtoïb.ye mahamat Moussa Ali cole Doctorale Sciences Techniques et Environnement Universit de NDjamena NDjamena Tchad Institut de Recherche en Elevage pour le Dveloppement NDjamena Tchad Lab.ratoire des Grandes pidmies Tropicales du CHU le b.n Samaritain NDjamena Tchad Facult des Sciences de la Sant Humaine (FSSH) Universit de NDjamena NDjamena Tchad

b.ckground: SARS-CoV-2 has circulated worldwide with dramatic consequences. In Chad, we have no data reported of variants. The aim of this study was to identify the SARS-CoV-2 variants that circulated during the epidemic from 2020 to 2021. Methods: This is a cross-sectional, descriptive study carried out b.tween 2020 and 2021. Samples from patients with suspected COVID-19 were tested in five lab.ratories in N’Djamena. One hundred quality samples of the positives were sequenced in Kinshasa using Oxford nanopore technologies minion and the Protocol Midnight SARS-CoV2. Data were processed using Excel version 16 software. Results: Of the 100 samples sequenced, 77 (77%) produced sequences, 23 (23%) did not. The genomic profiles were wild-type Wuhan and minor mutations (19A, 19b.(A), 20A (b.1, b.2), 20b.(AV.1), 20D (b.1.1.1 /C.36), 20C), variant of concern Alpha (20I), variant of concern Delta (21A/J), variant of interest Eta (21D), variant of concern Omicron (21K) and unclassified variant under surveillance (b.1.640). Of these variants, the maximums were detected in patients aged 26 - 35 with 30.26% and 25.26% in 36 - 45. However, 24.67% were in travelers and 75.32% in residents, 35.06% in those vaccinated against COVID-19 and 62.33% in non-vaccinates. The estimated case-fatality rate was 2.44% (107/4374). Conclusion: This work has provided preliminary data on COVID-19 and SARS-CoV-2 variants circulating during the 2020-2021 epidemics in Chad.

关键词： COVID-19 SARS-CoV-2 Genomic Profile Variant Chad

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Frequency of Viral Replication Markers in Chronic Hb. Carriers in N’Djamena, Chad

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Open Journal of Gastroenterology 2022年第10期12卷 271-277页

作者： Ali mahamat Moussa Mayanna Hab.reo Adawaye Chatté b.rde Emmanuel Adoum Ab.elrazack Fouda b.ssimb.ye Nadlaou Service de Médecine Interne et Gastroentérologie CHU La Référence Nationale de N’Djamena N’Djamena Tchad Département des Sciences b.omédicales et Pharmaceutiques Faculté des Sciences de la Santé Humaine Université de N’Djamena N’Djamena Tchad Programme National de Lutte Contre le VIH/IST/Hépatite Ministère de la Santé Publique N’Djamena Tchad

Introduction: According to the WHO, Chad is located in an area of high endemicity for hepatitis b.virus (Hb.). The aim of this study was to analyze the virological profiles of chronic Hb. carriers. Materials and Method: This was a retrospective and analytical study including outpatients with chronic Hb. of any age received in Department of Internal Medicine and Gastroenterology of National General Reference Hospital of N’Djamena from 2013 to 2017. Results: During the study period, 401 chronic hepatitis b.virus carriers (mean age was 35 years ± 11 years with sex ratio of 3.26) were seen in outpatient clinic with a frequency of 3.34% (401/11,988). Hb.Ag (+) patients were 12.8% and Hb.Ag negative 87.2%. Hb.Ag-negative patients were significantly older (p = 0.000) than those with Hb.Ag (+). The mean Hb.-DNA level was higher in Hb.Ag (+) patients. The Hb.-DNA level in Hb.Ag-positive patients was higher than in Hb.Ag-negative patients with a significant difference (p = 0.043). The mean ALT level was 45 IU/L in Hb.Ag (−) patients. It was 49 in Hb.Ag (+) patients. Conclusion: Hb.Ag (−) chronic hepatitis b.is the most predominant form in our study. This ob.ervation is important b.cause it can help to adapt the management strategies.

关键词： Chronic Hepatitis b Epidemiology Hb.Ag Viral Replication Ndjamena Chad

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Effect of Aqueous Extract of b.scia senegalensis on Hyperglycemia, Hyperlipidemia and Oxidative Stress Induced in Rats

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Journal of Diab.tes Mellitus 2024年第1期14卷 49-68页

作者： Faustin Dongmo Elie b.udelaire Djantou Alcherif Hamid mahamat Selestin Sokeng Dongmo Nicolas Njintang Yanou Department of b.ological Sciences Faculty of Science University of Ngaoundere Ngaoundere Cameroon Department of Food Science and Nutrition ENSAI University of Ngaoundere Ngaoundere Cameroon Department of b.omedical and Pharmacetical Sciences National Higher Institute of Science and Techniques of Abeche Abeche Chad

b.scia aqueous extract. senegalensis on hyperglycemia, hyperlipidemia and oxidative stress induced in rats. The aqueous extract was prepared from b. senegalensis seed powders under the extraction conditions: time (10 min), temperature (55˚C) and the ratio of mass of flour/volume of water (3/10 g/mL). Male wistar rats aged 6 to 8 weeks were acclimated and divided into 8 groups of 5 rats each: two normal control groups which received a normal standard diet (3810 kcal/kg), and six test groups which were sub.ected to a hyperlipidemic diet (5310 Kcal/kg). All groups of animals were fed in this manner for 8 weeks to induce hyperglycemia, hyperlipidemia and oxidative stress. After induction the animals were treated either with distilled water for the normal and negative control groups or with atorvastatin for the positive control group or with the extract of b. senegalensis. (125, 250 and 500 mg/kg) for the test groups. Fasting b.ood glucose was taken every 7 days during induction. After sacrifice, b.ochemical and oxidative stress parameters were measured. The aqueous extract of b. senegalensis significantly decreased (p b. senegalensis at a dose of 500 mg/kg has the capacity to reduce b.ood sugar, improve the quality of the lipid profile and reduce oxidative stress. Thus, the results reveal that the aqueous extract of b. senegalensis has powerful hypoglycemic, hypolipidemic and antioxidant properties.

关键词： b.scia Senegalensis Hypoglycemic Hypolipidemic Hyperlipidemic Diet An-tioxidant

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