Proxy contests: Prospects and challenges for corporate governance in Nigeria

The legal authority for management and direction of a company rests with the board of directors, whose duty it is to supervise the general course of business, and to use its powers in the best interests of the company. However, ultimate power resides in the shareholders as the board is brought into managerial office by them via elections in annual general meetings. Yet, whenever the shareholders are dissatisfied with the manner the board of directors is conducting and managing the affairs of the company, such management can be ousted through voting it out during another election. By this, shareholders need no longer be content to sit on the sideline and watch as their shares in a company plummet; they are rather standing up and holding management accountable. This study seeks to explore the theory and practice of 'proxy contest', investigates its application in some other jurisdictions, and considers its prospects and challenges with a view to adopting the practice into Nigerian corporate governance.Keywords: Proxy contest, Corporate governance, Prospects, Challenges, Nigeri

Restoration of soil quality using biochar and brown coal waste: A review

Soils in intensively farmed areas of the world are prone to degradation. Amendment of such soils with organic waste materials attempts to restore soil quality. Organic amendments are heterogeneous media, which are a source of soil organic matter (SOM) and maintain or restore chemical, physical, biological and ecological functionality. More specifically, an increase in SOM can influence the soil microclimate, microbial community structure, biomass turnover and mineralisation of nutrients. The search is on-going for locally sourced alternatives as many forms may be costly or geographically limiting. The present review focuses on a heterogeneous group of amendments i.e. biochar and brown coal waste (BCW). Both biochar (made from a variety of feedstocks at various temperatures) and BCW (mined extensively) are options that have worldwide applicability. These materials have very high C contents and soil stability, therefore can be used for long-term C sequestration to abate greenhouse gas emissions and as conditioners to improve soil quality. However, biochar is costly for large-scale applications and BCW may have inherently high moisture and pollutant contents. Future studies should focus on the long-term application of these amendments and determine the physicochemical properties of the soil, bioavailability of soil contaminants, diversity of soil communities and productivity of selected crops. Furthermore, the development of in situ technologies to lower production and processing costs of biochar and BCW would improve their economic feasibility for large-scale application

The role of biochar in enhancing safe use of untreated wastewater in agriculture

In many developing countries, water scarcity and the growing population are becoming problematic. Therefore, the reuse of wastewater for irrigation provides an alternative management option. Irrigation with poorly treated or untreated wastewater could, however, pose risk to human health due to the presence of a wide range of contaminants, including heavy metals, which can move into the edible parts of various crops such as potatoes (Solanum tuberosum L.) and spinach (Spinacia oleracea L.).The study aimed to investigate biosorbent role in the remediation of heavy metals in soil and crops irrigated with untreated wastewater. Both aboveground and belowground crops were selected to better assess the effect of rooting system on the plant uptake of heavy metals.To achieve this goal, a field lysimeter experiment was undertaken to elucidate the fate and transport of six water-borne heavy metals (Cd, Cr, Cu, Fe, Pb and Zn) in irrigation water applied to potatoes (cv. Russet Burbank) and spinach grown on a sandy soil. Plantain peel biochar (1% w/w) was incorporated in the top 0.1 m of soil. All the control and biochar treatments were replicated three times in a completely randomized design carried out on nine outdoor PVC lysimeters (1.0 m height × 0.45 m diameter).In a two-year study, potatoes were planted, irrigated at 10-day intervals, leachate samples were collected, followed by soil samples collected two days after each irrigation. Results showed that all heavy metals accumulated in the top soil; Fe, Pb and Zn were detected at 0.1 m depth; while only Fe was detected at 0.3 m depth. No heavy metals were detected in the leachate. Matured potatoes were harvested and separated into flesh, peel, leaf, stem and root. Results indicated that heavy metals translocated to all parts of the potato plant. The heavy metals were relatively low in the potato parts under freshwater (vs. wastewater). Biochar-amended-soil significantly (p<0.05) reduced only Cd and Zn in tuber flesh (69% and 33%, respectively) and peels compared to the non-amended wastewater control. Interestingly, biochar amendment, after the second season significantly (p<0.05) reduced Cd, Cu, Cr, Pb and Zn in the edible flesh.As an example of aboveground crops, spinach was planted in lysimeters, irrigated every 10 days and harvested twice for heavy metal analysis. Results showed that biochar amendment improved CEC and increased the pH of the soil, which resulted in a 42% reduction of Zn in spinach leaves. The impact of biochar on translocation of other heavy metals (Cd, Cu, Cr, Fe, and Pb) to spinach leaves was at minimum, possibly due to competition with other compounds in the soil solution.The effect of biochar on potato yield was also studied for the two seasons. It was found that: (1) In the first season, the yield was significantly less in the biochar treatment, possibly due to germination delay in the biochar amended lysimeters. (2) In the second season with no germination delay observed, the yield was similar in the presence and absence of biochar. Of note, yields were not affected even though significantly higher (p<0.05) heavy metals were taken up by different parts of the potato plants under wastewater irrigation (vs. freshwater). This can be alarming to some degree as the farmer may be getting the expected yield but with unhealthy potatoes, and not realizing this at all. It was concluded that effect of plantain peel biochar on the plant health parameters and yield of potatoes was not significant.Overall, biochar amendment, with improved pH and CEC, showed high potential in the immobilization of heavy metals in soil, thereby reducing their uptake by plants. Therefore, the application of biochar as a soil amendment could result in a safer use of wastewater irrigation for crops. The accumulation of heavy metals in soil and uptake by plant parts, however, were crop dependent.Face aux pénuries en eau et une rapide croissance démographique, chacun problématique dans plusieurs pays en voie de développement, la réutilisation des eaux usées pour l'irrigation offre une alternative de gestion permettant de conserver les ressources en eau. Cependant, l'irrigation avec des eaux usées insuffisamment ou non traitées présente un risque à la santé humaine puisque plusieurs contaminants, dont les métaux lourds, peuvent se retrouver dans ou sur les parties comestibles de diverses cultures tels les pommes de terre (Solanum tuberosum L.) et épinards (Spinacia oleracea L.).La présente étude visa à éclaircir le rôle des sorbants biologiques dans la restauration des sols et cultures contaminés avec des métaux lourds par voie de leur irrigation avec des eaux usagées non-traitées. Des cultures comestibles furent choisis afin de mieux évaluer l'effet du système racinaire sur l'assimilation de métaux lourds par une culture. Les pommes de terre furent plantées, irrigués aux 10 jours, des échantillions de lixiviat prélevés, puis des échantillons de sol prélevés 2 jours après chaque irrigation. Tous les métaux lourds s'accumulèrent dans la couche supérieure du sol: le Fe, Pb, et Zn étant détectés à une profondeur de 0.1 m, puis le Fe détecté jusqu'à une profondeur de 0.3 m. Aucun métal lourd ne fut détecté dans le lixiviat. Les pommes de terre furent récoltées à maturité et séparés en chair, pelure, feuille, tige et racine. On retrouva des métaux lourds à travers toutes les plants de pomme de terre, mais à des niveaux plus bas pour les plants irrigués avec de l'eau douce plutôt que des eaux usées. Par rapport au témoin sans biochar, l'ajout de biochar au sol diminua de façon significative (p<0.05) les teneurs en Cd et Zn de la chaire des tubercules (69% et 33%, respectivement) ainsi que celle des pelures. Après la seconde saison de culture, l'ajout de biochar diminua (p<0.05) les teneurs en Cd, Cu, Cr, Pb and Zn de la chair comestible.Comme exemple de culture en surface, des épinards furent plantés dans les lysimètres. Cette culture fut irriguée aux 10 jours et les feuilles échantillonnées à deux occasions pour une analyse de métaux lourds. L'ajout de biochar au sol améliora son CEC et augmenta son pH, donnant lieu à une réduction de 42% du Zn dans les feuilles. L'effet d'un ajout de biochar au sol n'eut qu'un effet minime sur le mouvement des autres métaux lourds (Cd, Cu, Cr, Fe, and Pb) vers les feuilles d'épinards, le résultat probable de leur compétition avec d'autres cations dans la solution du sol.L'effet d'un ajour de biochar sur le rendement des pommes de terre fut évalué sur une période de deux saisons. Il est à noter que ce manque de différence en rendements (avec/sans biochar) eu lieu même si les différentes parties des plants ayant reçu des eaux usées montrèrent tous une accumulation de métaux lourds significativement (p<0.05) plus élevé que dans les plants irrigués avec de l'eau douce. Ceci pourrait être préoccupant, puisqu'un producteur pourrait atteindre le rendement attendu, tout en ayant produit des pommes de terre insalubres sans le savoir. Il est à conclure que l'ajout de biochar de pelures de plantain au sol à un taux de 1% n'eut aucun effet significatif, ni sur l'aspect santé des pommes de terre, ni sur leur rendement. L'ajout du biochar, augmenta le pH et la CEC du sol, mais ces impacts positifs furent masqués par une suffisance d'éléments nutritifs dans le sol.En général, l'ajout de biochar démontra un potentiel élevé pour immobiliser des métaux lourds dans le sol, réduisant ainsi leur assimilation par les plantes. L'accumulation de métaux lourds dans le sol et leur assimilation et distribution à travers la plante différa selon l'espèce cultivée. Potentiellement, l'ajout de biochar au sol permettrait donc une utilisation plus sécuritaire des eaux usées pour l'irrigation de certaines cultures

Optimization and mechanistic kinetic model : toward newsprint waste conversion to levulinic acid

In this study, Box-Behnken design was employed to optimize the yield of levulinic acid from HCl pretreated (HCl-NP) and Fenton pretreated (Fenton-NP) newsprints. Experiments were performed in a 5 mL Pyrex tube batch reactor at the following conditions: 180-200 ⁰C of reaction temperature (T), 3.5-4.5 h of reaction time (t), 0.1-0.2 M of catalyst concentration ([FeCl₃*6H₂O]), and 20-wt% LiCl, which served as a promoter. With the optimum conditions for conversion of HCl-NP and Fenton-NP as follow: T = 200 ⁰C, t = 3.63 and 3.50 h, and [FeCl₃*6H2O] = 0.118 and 0.100 M, the predicted maximum yields of levulinic acid were 83.4 mol% and 86.4 mol %, respectively. This showed that the optimal conversion of HCl and Fenton-NP occurred at different processing conditions. A mechanistic model was developed where the experimental concentrations of cellulose, glucose, hydroxymethylfurfural, and levulinic acid were simulated to generate the model’s kinetic parameters. This provides a deeper insight into the various stages necessary to improve levulinic acid yields from newsprint wastes.

Chemo-catalytic transformation of cellulose and cellulosic-derived waste materials into platform chemicals

The transformation of lignocellulosic biomass and residues to valuable products is an important area of modern biotechnology. The residues can include industrial and municipal wastes, agricultural residues, forest residues and natural herbaceous plants. They are mostly composed of cellulose, hemicellulose, and lignin. Cellulose being the most abundant biopolymer on earth, it has been identified as an alternative to petroleum-based feedstock to produce platform chemicals. However, the use of cellulose is challenging due to its recalcitrance to dissolution. At present, the catalytic conversion of cellulose and cellulosic materials is studied by various research groups. This review outlines the procedures for the chemo-catalytic conversion of cellulose to help valorize paper wastes into platform chemicals. These platform chemicals include sorbitol, ethylene glycol, gluconic acid, lactic acid, levulinic acid, and hydroxymethylfurfural, among others. The recent advances on the design and the use of novel homogenous and heterogenous catalysts have been reported. Special attention has been given to heterogenous catalysts due to their green status and scale-up potential. Moreover, the potential to recycle and reuse pulp and paper for bioprocessing has also been reviewed. Finally, the current and future market scenarios for these platform chemicals have been discussed. If economically competitive, these building block chemicals could overtake their fossil-based counterparts

Semisynthetic production of hydroxymethylfurfural and furfural : the benefits of an integrated approach

In this study, an integrated mechanoenzymatic/catalytic approach was employed to produce furan-based platform chemicals from newsprint wastes. The holocellulose fraction of the newsprint was first hydrolyzed to monosaccharides using a commercial cellulases blend at 55 °C (enzyme loading of 45 mg/g of substrate or 4.5% w/w). Working with moist-solid enzymatic reaction with a short period (15 min) of ball milling followed by 24 h of static incubation greatly enhanced hydrolysis, affording glucose and xylose yields of 52 mol% and 22 mol%, respectively. The sugars in the hydrolysate were next dehydrated using AlCl₃.6H₂O (200 mg) as an eco-friendly catalyst. With stirring at 600 rpm and 150 °C, hydroxymethylfurfural and furfural were obtained in yields of 66 mol% and 67 mol%, respectively. Another aspect was the first-order kinetic model with two consecutive reactions which was sufficient to predict the decomposition of sugars (glucose and xylose) into hydroxymethylfurfural and furfural, respectively

Valorization of Decationized Newsprint to Levulinic Acid

As of today, most chemical products are fossil-based. The environmental concerns of fossil resources due to their constant misuse have led to the exploration of bio-based alternatives. Biomass comprising industrial and municipal wastes, agricultural residues, forest residues, and natural herbaceous plants can favorably replace fossil fuel to produce chemicals. In this study, softwood and hardwood pulps were used to synthesize levulinic acid. Prior to a dilute acid hydrolysis step, the wood pulps were decationized overnight with 0.2 M HCl. The effects of the major reaction conditions including reaction temperature, time, and HCl concentration on the yield of levulinic acid was studied via a central composite design. Levulinic acid yields from softwood and hardwood pulps reached 50.30 mol% and 68.85 mol%, respectively, at optimum reaction conditions. When newsprints were tested using the optimized parameters for softwood and hardwood conversion, levulinic acid yields of 66.25 mol% and 79.65 mol% were obtained, respectively. A kinetic model was developed to predict the yields of glucose, hydroxymethylfurfural, and levulinic acid from the HCl-pretreated newsprint. The analysis of the kinetic parameters and the results of the response surface methodology experiments provided optimized conditions for levulinic acid production