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Papers by Agnes Mbonyiryivuze

African Journal of Educational Studies in Mathematics and Sciences, 2018

This review paper discusses the reforms in science curricula particularly those related to physic... more This review paper discusses the reforms in science curricula particularly those related to
physics curricula which took place after the launch of the Sputnik by the Soviet Union in
1957. These reforms have started at national level as well as international level by establishing
curriculum facilities around the end of 1960s. This review informs science educators about
previous research in science curricular reforms, the struggles of global physics instruction
transformation starting from United State of America (USA) and United Kingdom (UK), and
current science/physics education researches. Recent advances in physics curriculum
development as well as some important science reform programmes that have been done in
Africa are also discussed. The paper also highlights the Competence Based Curriculum
developed by Ministry of Education- Rwanda Education Board. The paper updates
science/physics educators on evaluation of effectiveness of various instructional methods
used in the past facilitating the identification of potential reform approaches to be successful
in future. Some practical recommendations that can be used for effective teaching and
learning of science, especially for physics are also outlined.

African Journal of Educational Studies in Mathematics and Sciences , 2019

This paper reports science tutors' perceptions about science curriculum reforms occurred in Rwand... more This paper reports science tutors' perceptions about science curriculum reforms occurred in Rwanda from 1996 to 2013 in Teacher Training Colleges (TTCs). It also highlights their perceptions about challenges and factors for effective implementation of Integrated Science Curriculum (ISC). Data for the study were collected from 26 science tutors teaching ISC in 11 TTCs from 4 provinces using questionnaires and structured interviews. Results showed that a slim majority of science tutors were not resistant to curriculum reform. Even if most of science tutors were confident while teaching most of the topics in ISC, they have experienced some difficulties in teaching physics and cross-cutting domains related topics as well as practical activities. Other identified challenges include lack of qualified tutors to teach ISC in TTCs, insufficient contact hours allocated to ISC topics, tutors' heavy workload, lack of sufficient science laboratory equipment and materials. In addition to TTC libraries that are not well equipped, lack of textbooks and teacher's guides as well as lack of in-service tutors' trainings were stressed to be some of challenges. Even if it was found that most competencies, skills, knowledge and attitudes gained by student-teachers after completing ISC were highly rated by science tutors, communication skills and problem-solving skills that are claimed to be important skills needed by graduates of science in the workplaces were poorly rated. The recommended strategies to overcome the identified challenges include active involvement of TTCs' science tutors in designing and development of ISC. Moreover, all TTCs should be provided with qualified science tutors to teach ISC. Trainings for in-service science tutors, recruitment of qualified tutors, and provision of adequate facilities, libraries and well-equipped science laboratories for all TTCs are also recommended.

Melanin is a vital component of the human pigmentary system. The level of pigmentation of the hum... more Melanin is a vital component of the human pigmentary system. The level of pigmentation of the human skin, hair and eyes is mainly determined by the ability of specialized cells to synthesize the eumelanin and pheomelanin components. Eumelanin is considered to be a heterogeneous macromolecule of 5,6dihydroxyindole (DHI) and its 2-carboxylated form 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Photobiophysicists, photobiologists and photochemists have played major roles in understanding key melanin photo-properties. Recent electrical studies are shedding light on the ultrafast energy dissipation & the fundamental electronics of the melanin-like systems. The materials physicists are exploring the possibility to use melanin as a potential basis to design novel hybrid functional materials.

Materials Today

This study reports on a systematic investigation of the multi-scale hierarchical arrangements in/... more This study reports on a systematic investigation of the multi-scale hierarchical arrangements in/of the Sepia melanin nanospheres using ultrahigh resolution transmission electron microscopy combined with transmission and scanning electron microscopies. The morphological dynamic of the  particle  150nm in average diameter melanin nanoparticles seem to be governed by self-assembly phenomenon before and after their final growth stages.

The efficiency of Grätzel cell can be further improved by the anchoring groups, such as COOH to b... more The efficiency of Grätzel cell can be further improved by the anchoring groups, such as COOH to be adsorbed onto the TiO2 surface with a large electronic coupling. Some of the most efficient sensitizers are synthetic dyes including transition metal coordination compounds such as Ruthenium polypyridyl complexes because of their highly efficient metal-to-ligand charge transfer, suitable ground and excited state energy levels with respect to titanium dioxide conduction band energy. They also have intense and wide range absorption in whole visible range. Even if they present such attractive features, their synthesis process is costly and complicated and they are not environment friendly because they contain heavy rare metals which are undesirable from the point of view of environmental conservation aspects. Natural dye can be the best alternative as they have acceptable efficiency in comparison to that one of transition coordination compounds and their extraction can be done by simple procedures from flowers, leaves, fruits, animals and other natural products. Melanin as the major component Sepia Officinalis ink pigment cause strong interactions with the hydroxyl groups of a TiO2. Melanin possesses a broad band absorbance in UV and visible range up to infrared. It also possesses the COOH and OH groups which would be free to bind to the surface of TiO2. Moreover, melanin polymer has interesting properties such as a considerable spectral absorbance width due to the high degree of conjugation of the molecule. This paper reports results from X-ray diffraction (XRD), UV-Vis as well as Raman spectroscopy of sepia melanin for Grätzel cell application.

Melanins are difficult to characterize because of their intractable chemical properties and the h... more Melanins are difficult to characterize because of their intractable chemical properties and the heterogeneity in their structural features. Melanin pigments, in fact, are composed of many different types of monomeric units that are connected through strong carbon-carbon bonds. Its high insolubility and undefined chemical entities are two obstacles in its complete characterization. The morphological characterization and particle size distribution for sepia melanin by Scanning Electron Microscopy (SEM) on surface structure and Transmission Electron Microscopy (TEM) to confirm the morphology obtained from SEM was done. Both results show that Sepia melanin is formed by many aggregates agglomerated together. These aggregates are formed also by small spherical granules with different size distributions that have been determined using image-J software. The small granule diameter obtained from different TEM and SEM micrographs were 100-200nm. EDS reveals that C and O were the most abundant in sepia melanin with concentration average concentrations of about 57% and 24% respectively. The major compositions of sepia melanin are C, O, Na, Cl, while the minor are Mg, Ca, K, S and N. From TEM micrograph at high resolution, it was possible to measure the distance between polymers layers of sepia melanin using image-J software and it was 0.323 nm = 3.23 Å.

The synthesis of metallic nanoparticles is an active area of academic, application research as we... more The synthesis of metallic nanoparticles is an active area of academic, application research as well and nanotechnology. Different chemical and physical procedures that are currently used for synthesis of metallic nanoparticles present many problems. These problems include generation of hazardous by-products, use of toxic solvents, and high energy consumption. Biological synthesis of nanoparticles by bacterial, fungi, yeast, and plant extract is the best alternative to develop cost effective, less labor, non-toxic using more green approach, environmentally benign nanoparticles synthesis to avoid adverse effects in many nanomaterials applications. Among the various metal oxide nanoparticles, titanium dioxide nanoparticles have wide applications for dye-sensitized solar cells, in air and water purification, due to their potential oxidation strength, high photo stability and non-toxicity. Till now, titanium dioxide (TiO2) is the cornerstone semiconductors for dye-sensitized (DSSC) nanostructured electrodes for dye-sensitized solar cells. This paper reports an overview of synthesis of TiO2 nanoparticles by biological means for dye-sensitised solar cell application.

This study reports on a systematic investigation of the multi-scale hierarchical arrangements in/... more This study reports on a systematic investigation of the multi-scale hierarchical arrangements in/of the Sepia melanin nanospheres using ultrahigh resolution transmission electron microscopy combined with transmission and scanning electron microscopies. The morphological dynamic of the 􀂢􀁉particle􀂲 􀁡150 nm in average diameter melanin nanoparticles seem to be governed by self-assembly phenomenon before and after their final growth stages.

Talks by Agnes Mbonyiryivuze

Drafts by Agnes Mbonyiryivuze

African Journal of Educational Studies in Mathematics and Sciences, 2018

This review paper discusses the reforms in science curricula particularly those related to physic... more This review paper discusses the reforms in science curricula particularly those related to
physics curricula which took place after the launch of the Sputnik by the Soviet Union in
1957. These reforms have started at national level as well as international level by establishing
curriculum facilities around the end of 1960s. This review informs science educators about
previous research in science curricular reforms, the struggles of global physics instruction
transformation starting from United State of America (USA) and United Kingdom (UK), and
current science/physics education researches. Recent advances in physics curriculum
development as well as some important science reform programmes that have been done in
Africa are also discussed. The paper also highlights the Competence Based Curriculum
developed by Ministry of Education- Rwanda Education Board. The paper updates
science/physics educators on evaluation of effectiveness of various instructional methods
used in the past facilitating the identification of potential reform approaches to be successful
in future. Some practical recommendations that can be used for effective teaching and
learning of science, especially for physics are also outlined.

African Journal of Educational Studies in Mathematics and Sciences , 2019

This paper reports science tutors' perceptions about science curriculum reforms occurred in Rwand... more This paper reports science tutors' perceptions about science curriculum reforms occurred in Rwanda from 1996 to 2013 in Teacher Training Colleges (TTCs). It also highlights their perceptions about challenges and factors for effective implementation of Integrated Science Curriculum (ISC). Data for the study were collected from 26 science tutors teaching ISC in 11 TTCs from 4 provinces using questionnaires and structured interviews. Results showed that a slim majority of science tutors were not resistant to curriculum reform. Even if most of science tutors were confident while teaching most of the topics in ISC, they have experienced some difficulties in teaching physics and cross-cutting domains related topics as well as practical activities. Other identified challenges include lack of qualified tutors to teach ISC in TTCs, insufficient contact hours allocated to ISC topics, tutors' heavy workload, lack of sufficient science laboratory equipment and materials. In addition to TTC libraries that are not well equipped, lack of textbooks and teacher's guides as well as lack of in-service tutors' trainings were stressed to be some of challenges. Even if it was found that most competencies, skills, knowledge and attitudes gained by student-teachers after completing ISC were highly rated by science tutors, communication skills and problem-solving skills that are claimed to be important skills needed by graduates of science in the workplaces were poorly rated. The recommended strategies to overcome the identified challenges include active involvement of TTCs' science tutors in designing and development of ISC. Moreover, all TTCs should be provided with qualified science tutors to teach ISC. Trainings for in-service science tutors, recruitment of qualified tutors, and provision of adequate facilities, libraries and well-equipped science laboratories for all TTCs are also recommended.

Melanin is a vital component of the human pigmentary system. The level of pigmentation of the hum... more Melanin is a vital component of the human pigmentary system. The level of pigmentation of the human skin, hair and eyes is mainly determined by the ability of specialized cells to synthesize the eumelanin and pheomelanin components. Eumelanin is considered to be a heterogeneous macromolecule of 5,6dihydroxyindole (DHI) and its 2-carboxylated form 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Photobiophysicists, photobiologists and photochemists have played major roles in understanding key melanin photo-properties. Recent electrical studies are shedding light on the ultrafast energy dissipation & the fundamental electronics of the melanin-like systems. The materials physicists are exploring the possibility to use melanin as a potential basis to design novel hybrid functional materials.

Materials Today

This study reports on a systematic investigation of the multi-scale hierarchical arrangements in/... more This study reports on a systematic investigation of the multi-scale hierarchical arrangements in/of the Sepia melanin nanospheres using ultrahigh resolution transmission electron microscopy combined with transmission and scanning electron microscopies. The morphological dynamic of the  particle  150nm in average diameter melanin nanoparticles seem to be governed by self-assembly phenomenon before and after their final growth stages.

The efficiency of Grätzel cell can be further improved by the anchoring groups, such as COOH to b... more The efficiency of Grätzel cell can be further improved by the anchoring groups, such as COOH to be adsorbed onto the TiO2 surface with a large electronic coupling. Some of the most efficient sensitizers are synthetic dyes including transition metal coordination compounds such as Ruthenium polypyridyl complexes because of their highly efficient metal-to-ligand charge transfer, suitable ground and excited state energy levels with respect to titanium dioxide conduction band energy. They also have intense and wide range absorption in whole visible range. Even if they present such attractive features, their synthesis process is costly and complicated and they are not environment friendly because they contain heavy rare metals which are undesirable from the point of view of environmental conservation aspects. Natural dye can be the best alternative as they have acceptable efficiency in comparison to that one of transition coordination compounds and their extraction can be done by simple procedures from flowers, leaves, fruits, animals and other natural products. Melanin as the major component Sepia Officinalis ink pigment cause strong interactions with the hydroxyl groups of a TiO2. Melanin possesses a broad band absorbance in UV and visible range up to infrared. It also possesses the COOH and OH groups which would be free to bind to the surface of TiO2. Moreover, melanin polymer has interesting properties such as a considerable spectral absorbance width due to the high degree of conjugation of the molecule. This paper reports results from X-ray diffraction (XRD), UV-Vis as well as Raman spectroscopy of sepia melanin for Grätzel cell application.

Melanins are difficult to characterize because of their intractable chemical properties and the h... more Melanins are difficult to characterize because of their intractable chemical properties and the heterogeneity in their structural features. Melanin pigments, in fact, are composed of many different types of monomeric units that are connected through strong carbon-carbon bonds. Its high insolubility and undefined chemical entities are two obstacles in its complete characterization. The morphological characterization and particle size distribution for sepia melanin by Scanning Electron Microscopy (SEM) on surface structure and Transmission Electron Microscopy (TEM) to confirm the morphology obtained from SEM was done. Both results show that Sepia melanin is formed by many aggregates agglomerated together. These aggregates are formed also by small spherical granules with different size distributions that have been determined using image-J software. The small granule diameter obtained from different TEM and SEM micrographs were 100-200nm. EDS reveals that C and O were the most abundant in sepia melanin with concentration average concentrations of about 57% and 24% respectively. The major compositions of sepia melanin are C, O, Na, Cl, while the minor are Mg, Ca, K, S and N. From TEM micrograph at high resolution, it was possible to measure the distance between polymers layers of sepia melanin using image-J software and it was 0.323 nm = 3.23 Å.

The synthesis of metallic nanoparticles is an active area of academic, application research as we... more The synthesis of metallic nanoparticles is an active area of academic, application research as well and nanotechnology. Different chemical and physical procedures that are currently used for synthesis of metallic nanoparticles present many problems. These problems include generation of hazardous by-products, use of toxic solvents, and high energy consumption. Biological synthesis of nanoparticles by bacterial, fungi, yeast, and plant extract is the best alternative to develop cost effective, less labor, non-toxic using more green approach, environmentally benign nanoparticles synthesis to avoid adverse effects in many nanomaterials applications. Among the various metal oxide nanoparticles, titanium dioxide nanoparticles have wide applications for dye-sensitized solar cells, in air and water purification, due to their potential oxidation strength, high photo stability and non-toxicity. Till now, titanium dioxide (TiO2) is the cornerstone semiconductors for dye-sensitized (DSSC) nanostructured electrodes for dye-sensitized solar cells. This paper reports an overview of synthesis of TiO2 nanoparticles by biological means for dye-sensitised solar cell application.

This study reports on a systematic investigation of the multi-scale hierarchical arrangements in/... more This study reports on a systematic investigation of the multi-scale hierarchical arrangements in/of the Sepia melanin nanospheres using ultrahigh resolution transmission electron microscopy combined with transmission and scanning electron microscopies. The morphological dynamic of the 􀂢􀁉particle􀂲 􀁡150 nm in average diameter melanin nanoparticles seem to be governed by self-assembly phenomenon before and after their final growth stages.