Bujumbura, Burundi

University of Burundi

Bujumbura, Burundi

The University of Burundi is located in Bujumbura, Burundi. It is the only public university in Burundi. Most of its facilities are deteriorating and significantly damaged due to civil war. In its infancy, it was owned and operated by the Roman Catholic Church. Its enrollment is approximately 13,000. Wikipedia.

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This study examines asymmetries in the nexus among energy use, pollution emissions and real output in South Africa using a nonlinear ARDL model advanced by Shin et al. [48]. The findings suggest the presence of asymmetries in the nexus among the indicated variables in the short and long run. Negative and positive shocks of the variables have different effects in sign and magnitude. The findings further show that both energy use and CO2 emissions affect real output; therefore caution is needed when advocating energy and environmental policies in South Africa, and the presence of asymmetries in the relationships among these variables should be taken into account. Further studies are needed to shed more light on asymmetries in the nexus among these important variables. © 2017 Elsevier Ltd

Li Z.,Central China Normal University | Claver H.,Central China Normal University | Claver H.,University of Burundi
Optics Letters | Year: 2013

In this Letter, we show that digital optical phase conjugation might be utilized to construct a new kind of wavelength- selective switches. When incorporated with a multimode interferometer, these switches have wide bandwidth, high tolerance for fabrication error, and low polarization dependency. They might help to build large-scale multiwavelength nonblocking switching systems, or even to fabricate an optical cross-connecting or routing system on a chip. © 2013 Optical Society of America.

Li W.,Northeast Normal University | Zhang J.,Northeast Normal University | Guo H.,Nanjing University of Technology | Gahungu G.,Northeast Normal University | Gahungu G.,University of Burundi
Journal of Physical Chemistry C | Year: 2011

The grand canonical Monte Carlo (GCMC) method and high-level first-principle calculations are performed to investigate the role of a constrained channel of microporous organic molecular crystal in separating H2 from binary mixtures containing N2, CH4, or CO2. GCMC simulations show that the selectivity of N2, CH4, or CO2 over H2 is in the order of N 2/H2 < CH4/H2 < CO 2/H2, which is consistent with the order of isosteric heats of adsorption. Particularly at low pressure the selectivity is very high because CO2, CH4, or N2 initially occupies the preferential site in the channel with less sites left for H2. In addition, dispersion corrected density functional theory (DFT-D) is introduced to study the interaction energies and structural properties of the conjugated channel and gases. By comparing with the benchmark data of the coupled-cluster calculations with singles, doubles, and perturbative triple excitations [CCSD(T)] estimated at the complete basis set (CBS) limit, the proper functional is selected. The first-principle calculations confirm that the heterogeneous channel can hold CO2, CH4, or N2 much stronger than H2, suggesting the microporous organic molecular crystal is a good candidate for potential hydrogen purification. © 2011 American Chemical Society.

Bo X.,Northeast Normal University | Ndamanisha J.C.,University of Burundi | Bai J.,Northeast Normal University | Guo L.,Northeast Normal University
Talanta | Year: 2010

A simple and facile synthetic method to incorporate Pt nanoparticles inside the mesopores of ordered mesoporous carbons (OMCs) is reported. The Pt/OMCs nanocomposite was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and nitrogen adsorption-desorption. The results show that the incorporation of Pt nanoparticles inside the pores of OMCs does not change the highly ordered two-dimensional hexagonal mesostructure of OMCs matrix. Nonenzymatic amperometric sensor of hydrogen peroxide and glucose based on the Pt/OMCs nanocomposite-modified glassy carbon (GC) electrode is developed. Compared with the original OMCs-modified electrode, the Pt/OMCs-modified electrode displays improved current response towards hydrogen peroxide and gives linear range from 2 to 4212 μM. At an applied potential of -0.08 V, the Pt/OMCs nanocomposite gives linearity in the range of 0.5-4.5 mM glucose in neutral buffered saline solution. This glucose sensor also exhibits good ability of anti-interference to electroactive molecules. The combination the unique properties of Pt nanoparticles and the ordered mesostructure of OMCs matrix guarantees the enhanced response for hydrogen peroxide and glucose. © 2010 Elsevier B.V. All rights reserved.

Ndamanisha J.C.,Northeast Normal University | Ndamanisha J.C.,University of Burundi | Bo X.,Northeast Normal University | Guo L.,Northeast Normal University
Analyst | Year: 2010

A novel ordered mesoporous carbon-tetrathiafulvalene composite is synthesized. It is based on host-guest chemistry which utilizes synergic interactions between a nanostructured matrix of ordered mesoporous carbon (OMC) and the excellent electron donor properties of tetrathiafulvalene (TTF). It has been found that some interesting properties of OMC are improved. Especially the density of the edge plane-like defective sites, important groups responsible for the electrocatalytic activity towards some molecules, is increased on OMC-TTF composite. Moreover, this new material can be used to facilitate the heterogeneous electron transfer process. OMC-TTF was used, for the first time, to investigate the electrocatalytic reduction of oxygen. The results show that the electrocatalytic behavior of OMC-TTF is attributed to the unique physico-chemical properties of OMC and TTF. At the OMC-TTF modified electrode, the reduction proceeds by the direct four-electron pathway whereas at the OMC electrode the process is not direct. In order to show that the ability of OMC-TTF to promote the electron transfer can allow the application of this composite in many domains, an amperometric oxygen biosensor has been constructed based on OMC-TTF. It exhibits good response to dissolved oxygen with a large linear range and a very low detection limit. The interferences of ascorbic acid and uric acid are suppressed and the applied potential is positive enough to avoid perturbations of other electrochemically reducible compounds. The results above suggest that OMC-TTF has potential applications in the detection of dissolved oxygen and interesting properties of this composite may open up a new approach to study the electrochemical behavior of other biomolecules. © 2010 The Royal Society of Chemistry.

Ndamanisha J.C.,Northeast Normal University | Ndamanisha J.C.,University of Burundi | Guo L.-P.,Northeast Normal University
Analytica Chimica Acta | Year: 2012

With its well-ordered pore structure, high specific surface area and tunable pore diameters in the mesopore range, ordered mesoporous carbon (OMC) is suitable for applications in catalysis and sensing. We report recent applications of OMC in electrochemical sensors and biosensors. After a brief description of the electrochemical properties, the functionalization of the OMC for improvement of the electrocatalytic properties is then presented. We show how the ordered mesostructure of OMC is very important in those applications. The high density of edge plane-like defective sites (EDSs), oxygen-containing groups and a large surface area on OMC may provide many favorable sites for electron transfer to compounds, which makes OMC a potential novel material for an investigation of the electrochemical behavior of substances. Moreover, the structural capabilities of OMC at the scale of a few nanometers agree with immobilization of other electrocataytic substances. Interesting properties of this material may open up a new approach to study the electrochemical determination of other biomolecules. © 2012 Elsevier B.V.

Liu Y.,CAS Changchun Institute of Applied Chemistry | Sun X.,Qingdao Agricultural University | Gahungu G.,University of Burundi | Qu X.,CAS Changchun Institute of Applied Chemistry | And 2 more authors.
Journal of Materials Chemistry C | Year: 2013

A DFT/TDDFT investigation was performed on the electronic structures, basic photophysical properties and potential OLED applications of a series of Ir(iii) complexes [(fpmb)2Ir(fptz)] (1a), [(dfpmb)2Ir(fptz)] (2a), [(fpmb)2Ir(bptz)] (3a), [(dfpmb)2Ir(bptz)] (4a) [where H2fpmb = 1-(4-fluorophenyl)-2,3-dihydro-3-methyl-1H-benzo[d] imidazole; H2dfpmb = 1-(2,4-fluorophenyl)-2,3-dihydro-3-methyl-1H- benzo[d]imidazole; fptzH = 2-(5-(trifluoromethyl)-2H-1,2,4-triazol-3-yl) pyridine; bptzH = 4-tert-butyl-2-(5-(trifluoromethyl)-2H-1,2,4-triazol-3-yl) pyridine] and [(fbmb)2Ir(fptz)] (1b), [(dfbmb)2Ir(fptz)] (2b), [(fbmb)2Ir(bptz)] (3b), [(dfbmb)2Ir(bptz)] (4b) [where H2fbmb = 1-(4-fluorobenzyl)-2,3-dihydro-3-methyl-1H-benzo[d] imidazole; H2dfbmb = 1-(2,4-fluorobenzyl)-2,3-dihydro-3-methyl-1H- benzo[d]imidazole] bearing two conjugated and nonconjugated carbene ligands respectively and one blue-emitting chromophore that possesses a much larger ligand energy gap. It is found that the photophysical properties of these complexes are greatly affected by the properties of the adopted ligands. From 1b to 4b, the insertion of a saturated σ-bond methylene spacer into the carbene ligand renders an increase of the HOMO-LUMO energy gap, but relatively weak absorption intensities. The emission spectra are slightly influenced by the switch between conjugated and nonconjugated ligands. Furthermore, on the basis of the calculations, the significantly higher quantum yield of 2b and 3b with respect to 3a is also explained with the assistance of their larger metal contribution to the lowest excited states (MLCT%) and smaller S 1-T2 splitting energies (ΔES1-T 2). Besides, the designed complexes 1b and 4b are considered to be potential candidates as blue-emitting materials with good charge transfer properties and high quantum efficiency. © 2013 The Royal Society of Chemistry.

Nkurunziza H.,University of Burundi | Gebhardt A.,Klagenfurt University | Pilz J.,Klagenfurt University
Malaria Journal | Year: 2011

Background: Malaria is a major public health issue in Burundi in terms of both morbidity and mortality, with around 2.5 million clinical cases and more than 15,000 deaths each year. It is still the single main cause of mortality in pregnant women and children below five years of age. Because of the severe health and economic burden of malaria, there is still a growing need for methods that will help to understand the influencing factors. Several studies/researches have been done on the subject yielding different results as which factors are most responsible for the increase in malaria transmission. This paper considers the modelling of the dependence of malaria cases on spatial determinants and climatic covariates including rainfall, temperature and humidity in Burundi. Methods. The analysis carried out in this work exploits real monthly data collected in the area of Burundi over 12 years (1996-2007). Semi-parametric regression models are used. The spatial analysis is based on a geo-additive model using provinces as the geographic units of study. The spatial effect is split into structured (correlated) and unstructured (uncorrelated) components. Inference is fully Bayesian and uses Markov chain Monte Carlo techniques. The effects of the continuous covariates are modelled by cubic p-splines with 20 equidistant knots and second order random walk penalty. For the spatially correlated effect, Markov random field prior is chosen. The spatially uncorrelated effects are assumed to be i.i.d. Gaussian. The effects of climatic covariates and the effects of other spatial determinants are estimated simultaneously in a unified regression framework. Results: The results obtained from the proposed model suggest that although malaria incidence in a given month is strongly positively associated with the minimum temperature of the previous months, regional patterns of malaria that are related to factors other than climatic variables have been identified, without being able to explain them. Conclusions: In this paper, semiparametric models are used to model the effects of both climatic covariates and spatial effects on malaria distribution in Burundi. The results obtained from the proposed models suggest a strong positive association between malaria incidence in a given month and the minimum temperature of the previous month. From the spatial effects, important spatial patterns of malaria that are related to factors other than climatic variables are identified. Potential explanations (factors) could be related to socio-economic conditions, food shortage, limited access to health care service, precarious housing, promiscuity, poor hygienic conditions, limited access to drinking water, land use (rice paddies for example), displacement of the population (due to armed conflicts). © 2011 Nkurunziza et al; licensee BioMed Central Ltd.

Ndayiragije F.,University of Burundi | Van Assche W.,Catholic University of Leuven
Journal of Physics A: Mathematical and Theoretical | Year: 2013

Multiple Meixner polynomials are polynomials in one variable which satisfy orthogonality relations with respect to r > 1 different negative binomial distributions (Pascal distributions). There are two kinds of multiple Meixner polynomials, depending on the selection of the parameters in the negative binomial distribution. We recall their definition and some formulas and give generating functions and explicit expressions for the coefficients in the nearest neighbor recurrence relation. Following a recent construction of Miki, Tsujimoto, Vinet and Zhedanov (for multiple Meixner polynomials of the first kind), we construct r > 1 non-Hermitian oscillator Hamiltonians in r dimensions which are simultaneously diagonalizable and for which the common eigenstates are expressed in terms of multiple Meixner polynomials of the second kind. © 2013 IOP Publishing Ltd.

Liu Y.,CAS Changchun Institute of Applied Chemistry | Gahungu G.,University of Burundi | Sun X.,Qingdao Agricultural University | Qu X.,CAS Changchun Institute of Applied Chemistry | Wu Z.,CAS Changchun Institute of Applied Chemistry
Journal of Physical Chemistry C | Year: 2012

A DFT/TDDFT investigation was applied to understand the unusual properties of the recently synthesized blue-emitting Ir(III) complexes [Ir(PMe 2Ph)(dppit)(py2pz)] (1) [PMe2Ph = dimethylphenylphosphine; dppit = diphenyl phenylphosphonite; py2pz = 3,5-di(2-pyridyl)pyrazole] and [Ir(PMe2Ph)(dppit)(bptz)] (2) [bptz =3-tert-butyl-5-(2-pyridyl) triazolate], which are successfully used as emitters in organic light-emitting diodes (OLEDs). The influence of N-substitution on optical and electronic properties of Ir(III) complexes was also explored by introducing a N atom on the pyridine moiety of Nâ̂§N ligands for 1 and 2. The calculated results reveal that introduction of N substitution leads to a blue shift for 1a, 1b, 1c, and 1d (a, b, c, d indicate different positions for N substitution) and slightly red shift for 2a-2d in absorption spectra compared with that of 1 and 2, respectively. The N substitution at different positions on Nâ̂§N ligands may also be an efficient approach of tuning emitting color for 1 and 2. The 1-position substituent (1a and 2a) leads to an obvious blue shift of emission spectra compared with 1 and 2, while a significant red shift is observed for the 3-substituted derivatives 1c and 2c. It is believed that the larger 3MLCT-3MC energy gap and higher μS1 value, as well as the smaller ΔES1-T1 for 1a/2a, are good indications for the higher quantum efficiency compared with that of experimental structures 1/2. These new structure-property relationships can provide improved design and optimization of OLED devices based on blue-emitting phosphorescent Ir(III) complexes. © 2012 American Chemical Society.

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