Kinetics of Cu2+– Catalysed Redox Reaction of n-(2-hydroxylethyl) ethylenediaminetriacetatocobalt(III) with Hydrazine Monohydrate in Aqueous Acid

Communication in Physical Sciences 2018, 3(1): 10-17 Received 24 November 2017/Accepted 23 July 2018 Authors: A. D. Onu, S. O. Idris & B. Y. Abiti The kinetics of the Cu2+-catalysed redox reaction between n-(2-hydroxylethyl) ethylenediaminetriacetatocobalt(III) (hereafter [Co(HEDTA)OH2]) with hydrazine monohydrate (hereafter N2H5+) have been successfully investigated in aqueous acidic medium, under the following conditions T = 298 ± 1 K, I = 0.5 mol dm3 (NaClO4), [H+] = 4.0 × 10-3 mol dm-3 (HClO4), [Cu2+] = 5.0 × 10-4 mol dm-3 and λmax = 550 nm. Stoichiometric study revealed that two moles of [Co(HEDTA)OH2] reacted with one mole of N2H5+.The rate of the reaction was first order with respect to [Co(HEDTA)OH2] and [N2H5+], and second order overall, with k2 = (9.81 ± 0.14) × 10-2dm3 mols-1. The rate of the reaction was inversely dependent on [H+] but directly proportional to [Cu2+] and both plots of k2 versus [H+]-1 and k2 versus [Cu2+] were linear from the origin, indicating a one term rate law with respect to both [H+]-1 and [Cu2+]. Changes in ionic strength had no effect on the reaction rate and temperature dependent study gave values of activated enthalpy (ΔH‡) and entropy (ΔS‡) as 82.89 KJ mol-1 and 17.13JK-1 mol-1respectively. Spectroscopic and kinetic investigations indicated absence of detectable intermediate. Analysis of evidence adduced from the study favour the outer-sphere mechanism and it is proposed for the reaction

Kinetics and mechanistics steps to the electron transfer reaction of peroxo-bridged binuclear cobalt(III) complex of succinimide by glycine in aqueous acidic medium

ABSTRACT. The kinetics and mechanistic steps to the electron transfer reaction of the peroxo-bridged binuclear cobalt(III) complex of succinimide [(suc)(en)2Co(O2)Co(en)2(suc)2+] hereafter called peroxo-bridged dicobalt(III) complex ‘[Co(O2)Co2+]’ by glycine have been carried out spectrophotometrically at λ = 420 nm and T = 26 ± 1 oC, [H+] = 1 x 10-3 M and ᶙ = 0.5 M (NaCl) in aqueous acidic medium. The reaction was found to be first order with respect to [Co(O2)Co2+] and [(Gly] and experimental data indicates a second-order overall. The reactions obeyed the general rate law: (d[Co(O2)Co2+]/dt) = (a +b)[H+])[Co(O2)Co2+][Gly]. Varying hydrogen ion concentration accelerated the reaction rate and shows first-order dependence while the reactions also affected by changes in the ionic strength of the reaction medium by giving a non-negative salt effect in the course of the reaction. Free radicals were not detected in the reactions. Spectroscopic investigation and Michaelis-Menten plots suggest the absence of intermediate complex formation. The experimental result obtained in this system is concluded in favor of the outer-sphere mechanism.                     KEY WORDS: Cobalt(III) complex, Kinetic, Electron transfer, Spectroscopic, Mechanistic steps, Michaelis-Menten, Glycine   Bull. Chem. Soc. Ethiop. 2021, 35(2), 425-434. DOI:  https://dx.doi.org/10.4314/bcse.v35i2.1

Kinetics and Mechanism of the Oxidation of Orange II by Chlorate Ion in Aqueous Hydrochloric Acid

Communication in Physical Sciences 2020, 5(2):165-170 Authors: B. Myek, S. O. Idris, A. D. Onu and M. K. Yakubu Received 05 March 2020/Accepted 03 May 2020 The kinetics of the oxidation of orange II (OR-) by ClO3-was studied in aqueous hydrochloric acid where the ionic strength and other parameters of the reaction mixture was, I = 0.50 mol dm-3 (NaCl), [H+] = 5.0 10-2 mol dm-3 (HCl) and T = 21 +/_ 1o C. The redox reaction displayed a stoichiometry of 1:2 and obeys the rate law given as,−????[????????−]/???????? = ????[????][????????][???????????? ]. The observed second order rate constant was found to increases with increase in hydrogen ion concentration. The rates of reaction displayed a zero salt effect and was inhibited by some added cations and anions. From the Michaelis-Menton Buck plot, there was no evidence for the formation of intermediate during the course of the reaction. Based on the results obtained, the outersphere mechanism was proposed for the reaction.&nbsp

IL-15 Participates in the Respiratory Innate Immune Response to Influenza Virus Infection

Following influenza infection, natural killer (NK) cells function as interim effectors by suppressing viral replication until CD8 T cells are activated, proliferate, and are mobilized within the respiratory tract. Thus, NK cells are an important first line of defense against influenza virus. Here, in a murine model of influenza, we show that virally-induced IL-15 facilitates the trafficking of NK cells into the lung airways. Blocking IL-15 delays NK cell entry to the site of infection and results in a disregulated control of early viral replication. By the same principle, viral control by NK cells can be therapeutically enhanced via intranasal administration of exogenous IL-15 in the early days post influenza infection. In addition to controlling early viral replication, this IL-15-induced mobilization of NK cells to the lung airways has important downstream consequences on adaptive responses. Primarily, depletion of responding NK1.1+ NK cells is associated with reduced immigration of influenza-specific CD8 T cells to the site of infection. Together this work suggests that local deposits of IL-15 in the lung airways regulate the coordinated innate and adaptive immune responses to influenza infection and may represent an important point of immune intervention

Factors influencing students’ choice of a federal university: a case study of a Nigerian federal university

The factors affecting students’ choice of higher education is essential for the university’s management. Various research across the world has been carried out to understand how students select their preferred universities for tertiary study; however, there is a shortage of insight from an African perspective. Specifically focusing on a federal university in Nigeria, this study aims to explore factors influencing students’ interest in the school and why they selected it as their study location. A structured questionnaire from 282 undergraduate students based on stratified random sampling was used to understand these choice factors. The study found that personal interest greatly influenced students’ decisions, followed by parental influence, university reputation, university ranking, and fees. The results provide an understanding of students’ choices for universities in a Nigerian context, which is a loose representation of the general influences of students’ choice for study sites on the continent. This would enable stakeholders working in the Nigerian education sector including academics, administrators and practitioners and international collaborators to understand the most effective ways to reach out to prospective students and draw useful lessons for universities' marketing strategies, which could be recommended not only in Nigeria but in Africa at large

The current state-of-the-art of spinal cord imaging: methods.

A first-ever spinal cord imaging meeting was sponsored by the International Spinal Research Trust and the Wings for Life Foundation with the aim of identifying the current state-of-the-art of spinal cord imaging, the current greatest challenges, and greatest needs for future development. This meeting was attended by a small group of invited experts spanning all aspects of spinal cord imaging from basic research to clinical practice. The greatest current challenges for spinal cord imaging were identified as arising from the imaging environment itself; difficult imaging environment created by the bone surrounding the spinal canal, physiological motion of the cord and adjacent tissues, and small cross-sectional dimensions of the spinal cord, exacerbated by metallic implants often present in injured patients. Challenges were also identified as a result of a lack of "critical mass" of researchers taking on the development of spinal cord imaging, affecting both the rate of progress in the field, and the demand for equipment and software to manufacturers to produce the necessary tools. Here we define the current state-of-the-art of spinal cord imaging, discuss the underlying theory and challenges, and present the evidence for the current and potential power of these methods. In two review papers (part I and part II), we propose that the challenges can be overcome with advances in methods, improving availability and effectiveness of methods, and linking existing researchers to create the necessary scientific and clinical network to advance the rate of progress and impact of the research