Amos Onasanya

Three-dimensional nickel nitride (Ni3N) nanosheets: free standing and flexible electrodes for lithium ion batteries and supercapacitors

The search for suitable electrode materials for electrochemical storage devices has led to the development of new electrode materials. Metal nitrides are regarded as an attractive and promising class of electrode materials for high-performance energy storage devices because they exhibit excellent electrical conductivity over the corresponding metal oxides and have considerably higher capacity than carbon based materials. Moreover, designing of different electrode nanostructures has been demonstrated to effectively improve the storage performance of energy storage devices. Hence, three dimensional (3D) nickel nitride (Ni3N) nanosheets were successfully fabricated on a carbon cloth by a simple hydrothermal and post annealing process that can be used directly as electrode storage materials for flexible lithium ion batteries and supercapacitors. Due to the electrode, architectures that demonstrated fast electron transport via direct connection to the flexible substrate and facile ion diffusion paths that ensured the participation of every nanosheet in the ultrafast electrochemical reaction, the 3D flexible Ni3N/carbon composites cloth exhibited a high capacity or capacitance and possessed an excellent rate performance.

A review of the development of full cell lithium-ion batteries: The impact of nanostructured anode materials

Lithium-ion batteries have emerged as the best portable energy storage device for the consumer electronics market. Recent progress in the development of lithiumion batteries has been achieved by the use of selected anode materials, which have driven improvements in performance in terms of capacity, cyclic stability, and rate capability. In this regard, research focusing on the design and electrochemical performance of full cell lithium-ion batteries, utilizing newly developed anode materials, has been widely reported, and great strides in development have been made. Nanostructured anode materials have contributed largely to the development of full cell lithium-ion batteries. With this in mind, we summarize the impact of nanostructured anode materials in the performance of coin cell full lithium-ion batteries. This review also discusses the challenges and prospects of research into full cell lithium-ion batteries.

Evaluation of acute and subacute toxicity of aqueous extract of Crassocephalum rubens leaves in rats

ETHNOPHARMACOLOGICAL RELEVANCE Crassocephalum rubens is found throughout tropical Africa including the Indian Ocean islands. The leaves are commonly eaten in form of soups and sauces in South-Western Nigeria, also in other humid zones of Africa. Traditionally, it is used as an antidote against any form of poisoning; used to treat stomach and liver complaints; and externally to treat burns, sore eyes, earache, leprosy and breast cancer. In this study, acute and subacute toxicity of aqueous extract of C. rubens leaves was evaluated in rats in order to assess its safety profile. MATERIALS AND METHODS In acute toxicity study, rats were given a single oral administration of aqueous extract of C. rubens leaves at graded doses (250-5000mg/kg). The animals were monitored for behavioural changes and possible mortality over a period of 24h and thereafter, for 14 days. In the subacute toxicity study, rats of both sexes were administered C. rubens orally at doses of 250mg/kg, 500mg/kg, 750mg/kg and 1000mg/kg body weight daily, for 28 days. Rats were observed weekly for any changes in general behaviour and body weights. In addition, other relevant parameters were assayed at the end of the main and reversibility study periods. RESULTS There was no observed adverse effect; including mortality in the animals. The extract caused no significant difference in the body weights as well as organs weights of treated groups when compared with the control groups. Haematological and biochemical parameters also revealed no toxic effects of the extract on rats. Histological assessments were normal in liver and kidney. CONCLUSIONS It can therefore be suggested based on the results from this study that aqueous extract of C. rubens leaves, at dosage levels up to 1000mg/kg, is non-toxic and could also offer protection on some body tissues. Aqueous extract of C. rubens could therefore, be considered safe. This study supports the application of Crassocephalum rubens in traditional medicine.

Antidiabetic potential of methanolic and flavonoid-rich leaf extracts of Synsepalum dulcificum in type 2 diabetic rats

Background Synsepalum dulcificum is a plant indigenous to West Africa. The fruit is used to modify taste of foods to sweetness. Objectives This study aims to investigate the antidiabetic potentials of both methanolic and flavonoid-rich leaf extracts of S. dulcificum (MSD and FSD respectively) in type 2 diabetic Wistar albino rats. Materials and methods Sixty three rats were randomly distributed into nine groups of seven animals each with group 1 serving as the normal control. Groups 2 to 7 were given 10% fructose in their drinking water for 14 days, after which 40 mg/kg of streptozotocin was administered. Group 2 animals served as the diabetic control, while groups 3, 4, 5, 6 and 7 were treated with 30 mg/kg MSD, 60 mg/kg MSD, 30 mg/kg FSD, 60 mg/kg FSD and 5 mg/kg glibenclamide respectively. Groups 8 and 9, contained healthy animals, and were treated with only 60 MSD, and 60 mg/kg FSD respectively. Biochemical parameters such as liver and kidney function tests, lipid profile, as well as lipid peroxidation and antioxidant enzymes were assessed in addition to histopathology. Results It was observed that daily oral administration of MSD and FSD for 21 days significantly (p < 0.05) improved the observed pathological changes as a result of type 2 diabetes. Conclusion It could be deduced from results obtained in this study that methanolic and flavonoid-rich leaf extracts of S.dulcificum have antidiabetic potential in type 2 diabetic rats.

Closed Anaerobic Biotransformation Products of Organoarsenic Compounds in Fucus distichus

The closed anaerobic decomposition extracts of Fucus distichus incubated with seawater and sediment, and without sediment as control, were subjected to extractions and isolation on Sephadex LH 20 and Cellulose Thin Layer Chromatography. The decomposition extracts and isolates were analyzed by using both the Hydride Generation Gas Chromatography Atomic Absorption Spectrometry (HG-GC-AAS) and High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry (HPLC-ICPMS) to identify the arsenic species in the equilibrium mixtures of the seaweed and filtrates separately. In the methanol seaweed extract, equilibrium mixture of arsenosugars (AS) AS1 and AS2 and their biotransformation products of dimethylarsinoylethanol (DMAE) and dimethylarsinic acid (DMAA) were identified. In the methanol filtrate extract of the mixture, only DMAE and DMAA were identified. However, in the control methanol filtrate extract five organoarsenic species, AS1 and AS2, one unidentified hidden organoarsenic species, DMAE and DMAA were identified in the equilibrium mixture. This result confirmed that the hidden organoarsenic species in Fucus distichus, AS1 and AS2, and an unidentified organoarsenic compounds are biotransformed to only DMAE and DMAA under an anaerobic condition. This also suggests that DMAE and DMAA are strong intermediate candidates for the generation of arsenobetaine, from arsenoribosides in the marine food webs.

Genetic Analysis and Molecular Identification of Virulence in Xanthomonas oryzae pv. oryzae Isolates

Bacterial leaf blight (BLB) of rice is a very destructive disease worldwide and is caused by Xanthomonas oryzae pv. oryzae (Xoo). The aim of the present study was to examine if the Xoo virulence pathotypes obtained using phenotypic pathotyping could be confirmed using molecular approach. After screening of 60 Operon primers with genomic DNA of two Xoo isolates (virulent pathotype, Vr, and mildly virulent pathotype, MVr), 12 Operon primers that gave reproducible and useful genetic information were selected and used to analyze 50 Xoo isolates from 7 West African countries. Genetic analysis revealed two major Xoo virulence genotypes (Mta and Mtb) with Mta having two subgroups (Mta1 and Mta2). Mta1 (Vr1) subgroup genotype has occurrence in six countries and Mta2 (Vr2) in three countries while Mtb genotype characterized mildly virulence (MVr) Xoo isolates present in five countries. The study revealed possible linkage and correlation between phenotypic pathotyping and molecular typing of Xoo virulence. Xoo virulence genotypes were known to exist within country and there was evidence of Xoo pathogen migration between countries. Durable resistance rice cultivars would need to overcome both Mta and Mtb Xoo virulence genotypes in order to survive after their deployment into different rice ecologies in West Africa.

Characterization of Arsenic Biotransformation Products from an Open Anaerobic Degradation of Fucus distichus by Hydride Generation Gas Chromatography Atomic Absorption Spectrometry and High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry

This work reports on the isolation and determination of biotransformation products obtained from the organoarsenic compounds that are present in Fucus distichus when it was subjected to an open anaerobic decomposition by using the Hydride Generation Gas Chromatography Atomic Absorption Spectrometry (HG-GC-AAS) and High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS). The seaweed and filtrate residues obtained from the open anaerobic degradation procedure were extracted in methanol and partitioned in phenol-ether-water mixtures to obtain water soluble extracts. The water soluble extracts were cleaned up and separated on a gel permeation Sephadex G15 column. Arsenic species concentrations were determined by using HG-GC-AAS. Final characterization of the biotransformation isolates was carried out on HPLC-ICP-MS. Only two arsenic species, 2-dimethylarsinoyl ethanol (DMAE) and dimethylarsinic acid (DMAA), were positively identified in the water soluble extract of the marine brown algae. The two arsenic species are strong intermediate candidates in the biosynthesis of arsenobetaine from oceanic arsenate in marine food webs.