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Search Results: 1 - 10 of 2536 matches for " Abdou Karim Diallo "
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Electrical Instability in Pentacene Transistors with Mylar and PMMA/Mylar Gate Dielectrics Transferred by Lamination Process  [PDF]
Abdou Karim Diallo, Abdoul Kadri Diallo, Diouma Kobor, Marcel Pasquinelli
Journal of Applied Mathematics and Physics (JAMP) , 2016, DOI: 10.4236/jamp.2016.47125
Abstract: This study deals with electrical instability under bias stress in pentacene-based transistors with gate dielectrics deposited by a lamination process. Mylar film is laminated onto a polyethylene terephthalate (PET) substrate, on which aluminum (Al) gate is deposited, followed by evaporation of organic semiconductor and gold (Au) source/drain contacts in bottom gate top contact configuration (Device 1). In order to compare the influence of the semiconductor/dielectric interface, a second organic transistor (Device 2) which is different from the Device 1 by the deposition of an intermediate layer of polymethyl methacrylate (PMMA) onto the laminated Mylar dielectric and before evaporating pentacene layer is fabricated. The critical device parameters such as threshold voltage (VT), subthreshold slope (S), mobility (μ), onset voltage (Von) and Ion/Ioff ratio have been studied. The results showed that the recorded hysteresis depend on the pentacene morphology. Moreover, after bias stress application, the electrical parameters are highly modified for both devices according to the regimes in which the transistors are operating. In ON state regime, Device 1 showed a pronounced threshold voltage shift associated to charge trapping, while keeping the μ, Ioff current and S minimally affected. Regardless of whether Device 2 exhibited better electrical performances and stability in ON state, we observed a bias stress-induced increase of depletion current and subthreshold slope in subthreshold region, a sign of defect creation. Both devices showed onset voltage shift in opposite direction.
Optimization of 6,13Bis(triisopropylsilylethynyl)pentacene (TIPS-Pentacene) Organic Field Effect Transistor: Annealing Temperature and Solvent Effects  [PDF]
Diallo Abdoul Kadri, Diallo Abdou Karim, Mané Seck, Kobor Diouma, Pasquinelli Marcel
Materials Sciences and Applications (MSA) , 2018, DOI: 10.4236/msa.2018.911065
Abstract: In this contribution, we report on the effect of solvents with different boiling points and annealing temperature on the performance of TIPS-pentacene transistors. Several solvents have been used for TIPS-pentacene thin film processing: toluene, chlorobenzene and tetrahy-drofuran. To study the influence of solvent and temperature; the electrical parameters of TIPS-pentacene field effect transistor were measured. The highest values of mobilities were 7.1 × 10-3 cm2·V-1·s-1, 4.5 × 10-3?cm2·V-1·s-1 and 1.43 × 10-3 cm2·V-1·s-1 respectively for TIPS-pentacene field effect transistor using chlorobenzene, toluene and tetrahydrofuran and annealed respectively at 120°C, 150°C and 120°C. We have correlated these electrical performances with AFM images in order to point out the role of morphological properties. It is found that the grain size, and roughness highly affect the electrical parameters.
Factors Associated with Death in Subjects Admitted for a Diabetological Emergency: Experience of the Medical Clinic II of the Abass Ndao Hospital Center in Dakar (Senegal) —Death in Diabetic Emergencies  [PDF]
Diédhiou Demba, Sow Djiby, Diallo Ibrahima Mané, Diallo Abdou Karim, Ndour Michel Assane, Sarr Anna, Ndour-Mbaye Maimouna, Diop Said Norou
Open Journal of Endocrine and Metabolic Diseases (OJEMD) , 2018, DOI: 10.4236/ojemd.2018.81005
Abstract: Introduction: Metabolic and vascular emergencies constitute a risk of lethality in diabetic subjects admitted to hospital. The objective was to evaluate the factors associated with death in subjects admitted for a diabetological emergency to improve management. Materials and Methods: It was a 12-month retrospective, descriptive and analytical study at Dakar’s Marc Sankale Diabetes Center. The study concerned any type of diabetics subjects admitted for a diabetological emergency. We evaluated the profile of diabetes, the pathologies found and factors associated with death. Results: We identified 697 cases of diabetic emergencies with a prevalence of 13.8%. The sex ratio (M/F) was 0.82, the mean age was 49.6 years, and the mean duration of diabetes was 7.1 years. The metabolic profile was hypoglycemia (11.3%), ketoacidosis (34.6%), and hyperosmolar hyperglycemia syndrome (5%). The associated pathologies were vascular (51.1%), infectious (65.3%), kidney function impairment (7.6%), anaemia (13.8%). During the follow-up, 94 patients died, as an annual frequency of 13.5% among diabetological emergencies. In univariate analysis, the factors significantly associated with death were age > 60 years [OR = 4.09 (2.6 - 6.41)], hyperglycemia [OR = 2.58 (1.50 - 4.4)], hyperosmolar hyperglycemia syndrome [OR = 10.5 (5.19 - 21.5)], septic diabetic foot [OR = 3.57 (2.24 - 5.66)]. Vascular pathologies that significantly associated with death were stroke [OR = 4.06 (2.10 - 7.81)], lower limb arteriopathy [OR = 3.25 (1.84 - 5.73)], cardiovascular collapse [OR = 6.85 (2.34 - 20)]. In addition to diabetes, the deceased patients had one (18%), two (34%) and at least three (45.7%) known factors of poor prognosis. Conclusion: Emergencies in diabetology remain frequent in our practice. The comorbidity (vascular and infectious) constitutes a risk of abnormally high death rate. A particular attention must concern on old diabetics subjects with several pathologies.
Study of the Thermal, Rheological, Morphological and Mechanical Properties of Biocomposites Based on Rod-Of Typha/HDPE Made up of Typha Stem and HDPE  [PDF]
Babacar Niang, El Hadj Babacar Ly, Abdou Karim Diallo, Nicola Schiavone, Haroutioun Askanian, Vincent Verney, Ansou Malang Badji, Mahmoud Kalid Diakite, Diéne Ndiaye
Advances in Materials Physics and Chemistry (AMPC) , 2018, DOI: 10.4236/ampc.2018.89023
Abstract:
The thermal, rheological and morphological properties of composite biomaterials made with mixture of high density polyethylene and typha rod powder (RD) were evaluated. The dynamic mechanical behavior of the samples was studied with 25%, 35% and 45% typha stem powder concentrations. The viscoelastic properties are mainly related to the nature of the polymer and the typha stem powder. Storage (G') and loss (G\") moduli increased significantly, depending on the amount of powder in the molten mixture. After a viscosity increase was noticed in low frequency, it decreased in high frequencies, which demonstrates the pseudo-plasticity effect. Morphological and thermal characterization results have shown the dispersion state of the powder and its ability to modify the kinetics crystallization of biocomposites.
The Effect of Poly-Ethylene-co-Glycidyl Methacrylate Efficiency and Clay Platelets on Thermal and Rheological Properties of Wood Polyethylene Composites  [PDF]
Ansou Malang Badji, El Hadj Babacar Ly, Diene Ndiaye, Abdou Karim Diallo, Ndickou Kebe, Vincent Verney
Advances in Chemical Engineering and Science (ACES) , 2016, DOI: 10.4236/aces.2016.64040
Abstract: Global ecological concerns have resulted in an interest in renewable natural materials. Composites based on high density polyethylene (HDPE), wood fiber (Veneer) and containing coupling agents like nanoclay (NC) and poly-ethylene-co-glycidyl methacrylate (PEGMA) were made by melt compounding and then injection molding. In this study, the effects of two variable parameters namely nanoclay and coupling agent on the rheological and thermal properties of wood polyethylene composites (WPECs) were investigated. The study investigates the morphology phase, rheology behaviors and thermal properties by scanning electron microscope, capillary rheometer and thermal gravimetric analyzer. The SEM micrographs of the composites showed that the outer surfaces of the wood were coated by a section of amorphous lignin. The state of dispersion in HDPE/pine/clay composites was improved by EGMA because it could interact with pine flour in addition to clay. The interaction of reinforcement with coupling agent and HDPE matrix is strong based on the observation of the fracture surface of composites when EGMA is present. However the addition of 2.5% clay slightly lowered the initial degradation temperature (Td) but did not improve the thermal stability. Obviously, all the composites materials exhibit viscoelastic values greater than those of neat HDPE.
Phosphorus Based Ceramics for Positive Electrode Synthesis and Characterization  [PDF]
Diouma Kobor, Abdou Kadri Diallo, Modou Tine
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.515147
Abstract: Historically, the LiCoO2 is the most used as active material for battery positive electrode because of its great potential (3.7 - 4.2 V), its interesting specific capacity (150 mA·h·g-1) and its excellent life cycle [1]. However, its toxicity, the cobalt cost and its structural instability oriented research towards new materials more stable that can replace it. In another context, hybrid, electrical vehicles and communication (computers and mobile phones...) have increased the scientific and technological research for new materials capable of storing and return energy through a system called accumulator. And research has identified the phosphate olivine structure as the most prolific ceramic material for positive electrode. LiFePO4 is a promising cathode material for Lithium-ion batteries. It provides high thermal stability and is synthesized using low cost materials. Unfortunately LiFePO4 suffers from a low electrical conductivity, which is harmful to its electrochemical performance. Decreasing the particle size, coating the particles with carbon or doping with metal atoms can increase the conductivity of the material. In this paper, we present the synthesis, physico-chemical and electrical characterization of lithium and iron doped Al-phosphorrus-based ceramic. The NPK Fertiliser was used as Al and phosphorus precursors. The powder XRD spectrum shows a possible presence of LiFePO4 and Fe2(PO)3 in theheterostrcture. An important quantity of Al is found by EDX spectra which supposed that the most important based atom is Aluminum and not Phosphorus. This can explain the increase of the conductivity value 102 times more important than those found in the literature for LiFePO4.
Efficacy of Different Fungicides against Mango Anthracnose in Senegalese Soudanian Agroclimate  [PDF]
Papa Madiallacke Diedhiou, Yaya Diallo, Rokhaya Faye, Abdou Aziz Mbengue, Abdou Sene
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.515236
Abstract:

Anthracnose is the one of the most devastating diseases of mango produced in the southern part of Senegal. The field trials against post harvest rot due to anthracnose took place in three orchards over two production seasons, in 2009 and 2010. Three systemic fungicides (thiophanate methyl, azoxystrobin and myclobutanyl) and one contact fungicide (mancozeb) were tested for their efficacy. The first treatments in 2009 took place in the rainy season, while 20% of mangoes on trees exhibited anthracnose lesions. At ripening stage, 100% of fruits from non treated control mango trees were affected by anthracnose and got rotten, while between 73.2% and 80% of mangoes ripened free of disease when treated with thiophanate methyl. With the treatment with azoxystrobin, between 46.6% and 60% of fruits were not infected. Treatment with myclobutanyl was less effective. This level of effectiveness was clearly improved in 2010 by preventive spraying, days ahead of onset of the rainy season, before the appearance of anthracnose symptoms on fruits. The level of effectiveness was higher respectively for thiophanate methyl (between 96% and 100% of fruits not infected) and azoxystrobin (between 84% and 96% of fruits not infected).

Comparative Analysis of Ranging Protocols for Localization by UWB in Outdoor  [PDF]
Salick Diagne, Thierry Val, Abdou Karim Farota, Bouya Diop
Wireless Sensor Network (WSN) , 2018, DOI: 10.4236/wsn.2018.105006
Abstract: The rapid evolution of technology in the field of wireless telecommunications and micro components using MEMS technologies (Micro-electromechanical systems) has contributed to the expansion and rapid development of wireless sensor networks (WSN). This rapid development has contributed to the appearance of sensor and actuator networks (WSAN) or even to the Internet of Things with DL-IoT (Device Layer-Internet of Things). This rapid evolution of WSN is due to the enthusiasm generated by this last in industry and research. This new technology is used in several applications, particularly in the outdoor location of communicating nodes. The process of distance calculation between nodes (ranging) is a primordial phase for a precise location of these nodes. This paper presents the result of measurements does with three ranging protocols (TWR, TWR_Skew and SDS-TWR) implemented on DecaWiNo nodes. DecaWiNo nodes use the Ultra-Wide Band (UWB) radio links, proposed by the IEEE 802.15.4 standard amendment of the year 2007, which provides a high-performance ranging by ToF (Time of Flight) [1] [2]. The results are very promising with precision errors of the order of 50 cm over 20 meters.
Traumatic Floating Bone. About 11 Cases and a Literature Review  [PDF]
Amadou Ndiassé Kasse, Malick Diallo, Souleymane Diao, Jean Claude Sane, Abdoulaye Bousso, Abdou Razack Ndiaye, Mouhamadou Habib SY
Open Journal of Orthopedics (OJO) , 2017, DOI: 10.4236/ojo.2017.712040
Abstract: Introduction: Floating bone injury or bipolar dislocation is a concurrent dislocation at both ends of a long bone or a flat bone. It is an exceptional injury. We report 11 consecutives cases of floating bones. Objectives: The aim of the study is to analyze the frequency, the mechanism of injury and clinical forms of floating bones, and to present the results of their management. Material and Methods: A ten years ongoing retrospective study was held in four trauma departments. Eleven cases of floating bones were identified. The floating bones characteristics such as the injured bone, the patient age and sex, the mechanism of injury, the dislocations directions, the associated complications, the treatment and the outcome were studied. Results: Nine male and two female patients, with a mean age of 37 years [19 - 65 years range] presented a concurrent bipolar dislocation of one bone or a group of bones. They sustained a road traffic accident (n = 5), a workplace accident (n = 3), a fall from height (n = 2), and a sport accident (n = 1). The clavicle (n = 3) and the first metatarsal (n = 3) were the most frequently involved. The others floating bones were the radius-ulna complex (n = 1), the radius-lunatum complex (n = 1), the first metacarpal (n = 1), the first phalanx (n = 1) and the femur (n = 1). The floating bones ends displacement occurred in the sagittal plane (the forearm, the femur, the first phalanx and the first metatarsal) and in the horizontal plane (the clavicle, the first metatarsal and the first metacarpal). We defined direction displacements as bidirectional asymmetric (n = 10) or unidirectional symmetric (n = 1). Associated complications were fractures (wrist, hip, tarso-metatarsal joints) and wounds (fingers, metatarso-phalangeal joint). Dislocations were treated conservatively (n = 5) and surgically (n = 17) with excellent results (n = 13/16 joints). Three patients were lost of view. Conclusion: Our study described the characteristics of this exceptional injury. For any joint dislocation, we promote the systematic examination of the other end of the dislocated bone.
Extremely Efficient Catalysis of Carbon-Carbon Bond Formation Using "Click" Dendrimer-Stabilized Palladium Nanoparticles
Didier Astruc,Cátia Ornelas,Abdou K. Diallo,Jaime Ruiz
Molecules , 2010, DOI: 10.3390/molecules15074947
Abstract: This article is an account of the work carried out in the authors’ laboratory illustrating the usefulness of dendrimer design for nanoparticle palladium catalysis. The “click” synthesis of dendrimers constructed generation by generation by 1à3 C connectivity, introduces 1,2,3-triazolyl ligands insides the dendrimers at each generation. Complexation of the ligands by PdII followed by reduction to Pd0 forms dendrimer-stabilized Pd nanoparticles (PdNPs) that are extremely reactive in the catalysis of olefin hydrogenation and C-C bond coupling reactions. The stabilization can be outer-dendritic for the small zeroth-generation dendrimer or intra-dendritic for the larger first- and second-generation dendrimers. The example of the Miyaura-Suzuki reaction that can be catalyzed by down to 1 ppm of PdNPs with a “homeopathic” mechanism (the less, the better) is illustrated here, including catalysis in aqueous solvents.
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