Phosphatase activity of soil as affected by cocoa pod ash

Results of the effect of cocoa pod ash and KHCO₃ on phosphatase activity of some cocoa soils of Ghana are reported. Phosphatase activity of control soils generally decreased with duration of incubation. Higher rates of the ash application, regardless of time, resulted in a lower phosphatase activity than the control. This inhibition, among other factors, may be due to the presence of high available P and certain cations such as Mn and Zn. The KHCO₃ increased the activity of the phosphatase in all soils when compared with the control.     

Pharmacokinetics of pentobarbital and thiamylal as combined anesthetics in sheep

This study was performed to investigate the possible mechanisms underlying prolongation of anesthesia times in sheep caused by the sequential administration of thiamylal and pentobarbital. Sodium thiamylal was injected as an intravenous bolus dose (13.2 mg/kg) followed in 7 min by sodium pentobarbital (14.3 mg/kg) by the same route to seven sheep. Separate studies were conducted for each of the two drugs administered separately to the same animals at the same doses. Mean anesthesia times (to the return of the palpebral reflex) were 7.89 min (thiamylal), 5.39 min (pentobarbital) and 34.1 min (the sequential combination). The kinetic parameters Vd(area), Vd(ss), t 1/2 beta, and ClB for either drug were not affected by the other when given in combination. The t 1/2 alpha was shorter, and the Vc was smaller, for pentobarbital when administered with thiamylal, while there were no changes in thiamylal disposition for the combination regimen. Computer-generated curves, associated with the two-compartment open model showing the fraction of dose in each compartment as a function of time, illustrated that pentobarbital rapidly achieved higher concentrations in the peripheral compartment after prior thiamylal administration. Protein-binding studies showed that this could not be attributed to displacement of pentobarbital from plasma albumin by thiamylal. Calculation of total and free drug concentrations at the time of awakening showed that, when the drugs were combined, the concentration of each drug was less than half of that observed at awakening when they were studied separately. It can be concluded that the prolonged sleeping times associated with the sequential combination of the two agents were not due to an alteration in kinetic parameters of either drug caused by the other, but rather to an additive effect of the subanesthetic concentrations of the two drugs when combined. The fact that sleeping times were supra-additive is attributed to a shift of awakening time from the distribution (alpha) phase, when given independently, to the elimination (beta) phase when administered in combination.     

Arylsulphatase activity of different latosol soils of Ghana cropped to cocoa (Theobroma cacao) and coffee (Coffea canephora var. robusta)

Summary A study was undertaken to investigate arylsulphatase activity in 15 soils cropped to cocoa (Theobroma cacao) and coffee (Coffea canephora var. robusta) in Ghana. The arylsulphatase activity was correlated positively and significantly with organic C, total N, and cation exchange capacity, and correlated negatively with acetate soluble sulphate. The enzyme was deactivated at an incubation temperature of over 60°C. Preheating and oven-drying of soils decreased arylsulphatase activity. Addition of 1.0 ml toluene during the assay resulted in a sharp decline in arylsuphatase activity. The addition of trace elements at a concentration of 1 ppm caused a reduction in soil arylsulphatase activity compared with that of the untreated samples.     

Changes in plant species composition within a planted forest in a deciduous agroecosystem in Ghana

Plantations provide a micro-climate that can facilitate the regeneration of other forest species. Often exotic species have been tested for these kinds of functions. To determine the potential for indigenous trees as plantation species for their ability to foster forest species regeneration, this study was undertaken in a mixed indigenous plantation stand. Understories of the stand at 8?years of age were surveyed for plant diversity. The species richness increased by 24% per 1,000?m² between 2001 and 2008 and the number of families represented increased by 48%. The Shannon Diversity and Simpson Index values confirm a greater diversity 8?years after the plantation was established. The most abundant species in study plots were Chromolaena odorata and Cedrela odorata, which collectively represent about 54% of all species identified in the plots. The most species-rich families were Fabaceae and Euphorbiaceae representing 31% of the total species recorded. Asteraceae and Meliaceae were the two most dominant families, which collectively represent about 55% of all species identified in the plots. 47 forest tree species were found per 1,000?m² but those classified as ??saplings?? occurred in low densities. The 47 tree species included pioneer species such as Entandrophragma angolensis, Milicia excelsa, and Ceiba pentandra. Growth rates of planted species were differed, with half of the tested species having similar growth capacity to the exotic species. Generally, planted indigenous species enhanced habitats for other forest tree species in degraded sites. The observed growth of indigenous species, if planted and protected, shows that they may help in biodiversity recovery within agricultural landscapes.     

Stability analysis of yield and aflatoxin accumulation resistance in maize using GGE biplot

Journal of Crop Science and Biotechnology - Maize (Zea mays L.) is the most important cereal crop in sub-Saharan Africa. However, its production is constrained by many factors including low yields...     

Farm Forestry Prospects Among Some Local Communities in Rachuonyo District,Kenya

Deforestation and degradation of productive lands are serious threats to the sustainability of forestry/agricultural practices in Kenya. In the last two decades farm forestry (FF) has been promoted through pilot projects among local communities as an example of sustainable land use. However adoption of FF is limited outside the project locations because FF improvement measures focused mainly on biological (e.g. succession, biodiversity and traditional industrial timber production) and technical concerns (e.g. material input delivery such as providing free tree seedlings for field planting) rather than local values, and interests and the constraints facing farmers. This study examined the local farm priorities and constraints and the prospects for the wider implementation of farm-level tree planting in four communities in Rachuonyo District. Using interviews with 597 randomly selected household heads, the study assessed farmer’s production assets and activities, land tenure, priority tree species and the constraints to growing trees on farms. Results show that farm labour is represented by a young population, 56.3% under the age of forty. They are mainly engaged in small-scale mixed cropping integrated with multipurpose trees and some livestock. Tree products contribute about 32% to household cash income, more than any other source (agricultural products, labour sales, etc). Females were more often household heads and had considerable influence over productive activities, making them an important target group in FF development. Farmers preferred exotic tree species due to their ability to provide short-term cash income, fuel and shade. Farmers’ concerns included population pressure on limited farmlands and the problem of credit for agricultural inputs. Given the feeling of secured tenure arrangement and influence of tree products on the household economy, farmers are likely to invest more in efficient land uses such as FF if consideration is given to local priorities.     

Numerical investigation on self-primingprocess of self-priming pump

In order to investigate the self-priming process of self-priming pump, an unsteady simulation was conducted where the Navier-Stokes equations were used with the Lagrangian-Eularian model. In course of this investigation, the volume fractions, pressure distribution and self-priming time were carried out. By analyzing the volume, velocity and pressure distribution of the gas-liquid two-phase flow at different time, the two-phase content via the variation law of the two-phase flow in the pump was carried out. By monitoring and analyzing the gas-liquid flow at the outlet of the pump, the self-priming time and crucial periods were given. Two phenomena were mainly characterized by the self-priming process such as the gas-liquid mixing and separation, which occur in the early stage of self-priming process. During that period the gas-liquid mixing clouds appear on the outer edge of the impeller, and the instantaneous void fraction at the inlet and outlet of the impeller decreases obviously. It was also established from the transient study that the effects of gas have a major influence on the hydraulic performance of the pump at the early stage of operation. To increase the usage of self-priming pump and to also understand the energy conversion of the pump it is very essential to investigate and establish the basic working principle of the self-priming pump.     

Some aspects of clinical pharmacokinetics in veterinary medicine. I

This series of two review articles deals with general aspects of the mechanisms which govern absorption and distribution of drugs within the body, and the kinetics of drug metabolism and excretion. Emphasis is given to the verification of pharmacokinetic principles in domestic animals, and the clinical applications which proceed therefrom. In the first part, the concept of the two compartment and three compartment models for drug disposition are introduced and developed to demonstrate the mathematical models which may be derived to describe the kinetics of drug distribution and elimination. In the second part bioavailability and drug dosage will be considered.