Freezing Curve Measurements For Hydrocarbon Mixtures

Solid-liquid equilibrium measurements were carried out for a binary system of (decane + dodecane) at several different mole fractions under atmospheric pressure. The work involved the design of new experimental setup for the solid-liquid equilibrium data measurements. The newly designed setup was used to study the freezing curve and solid-liquid transition temperature for pure decane and dodecane as test runs. The main work was to investigate and confirm the binary mixtures which form solid solutions (solid state structure) or eutectic structures (each particular component forms crystals out of the solution separately), and further develop a binary solid-liquid phase diagram for decane and dodecane. The experiment involved the use of an environmental chamber which housed a metal cell with the test liquid placed in it. Liquid samples were taken from the metal cell and analyzed in the Gas Chromatograph (GC) as the melting and freezing went on to determine their composition at various temperatures. The results from the experiment showed that the binary mixture forms a solid solution upon freezing. This was determined by withdrawing liquid samples from the metal cell and analyzing it in the GC as the liquid sample freezes. The liquid composition analyzed by the GC at every 2oC temperature drop turned out to have the same composition as the initial composition placed in the metal cell. This shows that the binary mixture freezes together at a particular temperature. The temperature profiles of several mole fractions were determined and were used to develop the solid-liquid binary phase diagram for decane-dodecane mixture

The changes and effect of stress hormone cortisol during extreme diet and exercise

Cortisol is one of the stress hormones produced as a result of stimulus to the hypothalamus triggering the hypothalamic-pituitary-adrenal axis (HPA).The result of cortisol production after this trigger is to return the body and its relevant systems back to homeostasis. This is a desired state of physiologic equilibrium in the body. A number of physiological and environmental conditions trigger the HPA pathway. This includes hypoglycemia (low blood sugar), dehydration (low blood volume), exercise, which are considered stress triggers, and changes to the circadian cycle. It is no wonder then that extreme diet and exercise can impact the HPA axis due to the stress caused by such activities or lifestyle choices. Fortunately, the production of cortisol in response to exercise has been extensively studied. Generally, studies have shown that the level of plasma cortisol levels increase proportionally during high intensity exercise, while a general decrease has been observed during moderate or low intensity exercise (Davis & Few, 1973). In addition, several scientific texts provide substantial information on the correlation between hypoglycemia and cortisol synthesis. This information in addition to other sources has proven useful for assessing the effect of extreme dieting on cortisol production. The aim of this thesis is to expand on the changes in cortisol caused by extreme exercise and diet as well as elaborate on the physiological effects that these cortisol levels in turn may have

Influence of dietary nutrients on life history-related traits of black flies and mosquitoes

The sugar-feeding ecology of dipteran vectors has recently been targeted because it presents opportunities to inoculate common food sources for these dipterans with entomopathogenic bacteria as a means of controlling the population of host-seeking adult dipteran vectors. Whereas this approach to vector control holds some promise, differences in the nutrient composition and concentration in sugary food sources can influence the food selection pattern of dipteran vectors and potentially confound the outcomes of field trials on the efficacy of entomopathogenic bacteria as vector control agents. Further, nutrient components of bacteria-inoculated artificial diets may present unintended effects of extending the survivorship or fecundity of the target population and potentially render the whole approach counterproductive. The present study investigated the diet-specific factors that influence the foraging decisions of female Simulium venustum/verecundum (Diptera: Simuliidae) and female Anopheles stephensi (Diptera: Culicidae) on artificial nectar and honeydew. Paired choice experiments showed that the black flies forage more frequently from high calorie diets, which contained melezitose, or those diets that contained amino acids, compared to low calorie melezitose-free diets or amino acid-free diets. The mosquitoes however displayed a more random diet selection pattern. The effects of sugary diets on certain life-history traits considered to be important to the ecological fitness of the black flies and mosquitoes were also investigated. Sugary diets had no significant effect on the survivorship and fecundity of the black flies, but they influenced the resistance of Leucocytozoon-infected flies to the parasite. Amino acid-containing diets appeared to extend the survival of mosquitoes, and also allowed them to take more vertebrate blood when they blood fed

Drivers of youth participation in commercial agriculture: a triple hurdle analysis of groundnut production and commercialization in northern Ghana

Youth unemployment, particularly in rural areas, is an albatross around the necks of many African countries. Creating opportunities along agricultural value chains has been identified as an entry point to countries’ efforts to improve rural livelihoods. However, youth are usually left out of agricultural market planning and programming. Previous studies on agricultural market participation have placed little emphasis on rural youth, despite their unique challenges and opportunities. Using a triple hurdle analytical approach, this study contributes to this discussion by examining the drivers of youth’s decision to participate in the production and commercialization of a high-value crop, groundnut, in Northern Ghana. Data from the seventh round of the Ghana Living Standards Survey (2016/2017) was used to achieve the study’s objective. The results show that agricultural output prices, access to transport services and road infrastructure; and favourable land tenure dynamics are positive determinants of youth’s participation in commercial agriculture. Interestingly, digital connectivity, level of education and gender (being female) are negative drivers of commercialization among young farmers. These results imply that policies that promote rural youth’s access to remunerative markets, productive assets, physical infrastructure, and transport services should be promoted. Importantly, ICT should be agro-customized in order for youth to fully take advantage of the opportunities that the current digital revolution presents to agriculture

Novel agmatine derivatives in Maerua edulis with bioactivity against Callosobruchus maculatus, a cosmopolitan storage insect pest

Food security in developing countries is threatened by crop pests and ectoparasites in livestock. Strategies for their management still rely on synthetic pesticides which are not always effective and the active ingredients persist in the environment with negative consequences for beneficial arthropods, farmers and consumers, hence necessitating research on sustainable alternatives. Botanical insecticides are increasingly relevant, typically having lower impacts on users, consumers and the environment. One example is the southern African shrub the Blue bush-berry, Maerua edulis. Recent work reported effective pest control using this plant species against cattle ticks, storage beetles and vegetable pests. However, little is known about the chemistry underlying activity and this is essential to optimize its use. Here, we identified two novel plant chemical tructures, the E and Z isomers of cinnamoyl-4-aminobutylguanidine along with the E and Z isomers of 4-hydroxycinnamoyl-4-aminobutylguanidine in the leaves of M. edulis. We isolated these compounds from the leaves and elucidated their chemical structures using various spectroscopic techniques including High Resolution Mass Spectrometry and Nuclear Magnetic Resonance Spectroscopy. We also identified a further 11 closely related structures of which 6 are tentatively reported here for the first time. Stachydrine and 3-hydroxystachydrine were also identified in the leaf extract, and occurred at very high concentrations; up to 2% w/w of dry leaves. We tested these two compounds, along with the 4 main cinnamoylamides and the crude M. edulis leaf extract against the cowpea bruchid Callosobruchus maculatus at concentrations equivalent to those present in extracts used by smallholder farmers. Mortality of insects exposed to crude plant extracts after 72 h was significantly higher than the untreated control although still lower than for insects exposed to rotenone, the positive control. The two new compounds and stachydrine showed similar activity to the crude extracts suggesting that these compounds explained the activity of the extract. After 6 days, the mortality of insects exposed to crude extracts and isolated compounds was similar to that recorded with the positive control. The stachydrine fraction and the E and Z isomers of cinnamoyl-4-aminobutylguanidine also inhibited oviposition activity in fecund female beetles. Our data show that methanol extracts of M. edulis were toxic to C. maculatus and inhibited oviposition even at 0.1% w/v so these foliar chemicals may explain the activity of the plant material. We also synthesized the amides which facilitated structural elucidation, produced adequate quantities for testing and demonstrated the potential for commercial synthesis

Fundamentals and Material Science Aspects of Particle Filled Polymer Blends

Filled polymers often comprise thermoplastic polymers and other particulate materials (particles) which are melt blended to form materials with improved mechanical, electrical or transport properties. In many such applications, the morphology of the blend plays a critical role in determining the properties of the blend. This dissertation seeks to exploit capillarity, i.e. interfacial tension forces, to control the microstructure of particle-filled plastics. For instance, by blending together two molten plastics and particles, a variety of structures including space-spanning aggregates, cocontinuous morphologies or fibrillar structures may be realized. These structures arise from a coupling between particle preference for one or both phases of the two immiscible polymers, interfacial tension and mixing conditions. This dissertation conducts fundamental studies of the relationship between morphology and composition of immiscible thermoplastic polymer blends filled with particles (fused and fumed silica) which are preferentially wetted by one of the polymers. The diverse microstructures that appear in different regions of the composition space are discussed, and morphological maps are constructed for such mixtures. The fundamental knowledge is then applied to develop materials in which the morphology has a significant effect on material properties. In one case, electrically conductive polymer composites are made, where a liquid metal alloy induces the aggregation of copper particles are forced to aggregate within a polymer matrix to form conductive pathways to improve the conductivity of the polymer. In another case, particles are aggregated in the presence of wetting polymer phase by capillary force to test for improvement in mechanical properties

Factors that Contribute to Motivation and Job Satisfaction of Lecturers in Selected Technical Universities in Ghana

In higher institutional dynamics lecturers’ motivation and job satisfaction are key factors. Generally, it is considered as primary variables which are used to evaluate the effectiveness of an institution’s human resource. The purpose of the study was to examine the factors that contribute to motivation and job satisfaction of lecturers in selected Technical Universities in Ghana. The descriptive survey designed was used for the study. The population of fulltime lecturers in Accra, Kumasi, Koforidua and Sunyani Technical Universities was 965. The stratified random sampling procedure which made use of the lottery method of simple random sampling was used to sample 400 fulltime lecturers. However, 356 respondents were captured for the study which resulted in 89.0 percent response rate. Questionnaire was the instrument used in eliciting data from the respondents. The Cronbach’s Alpha reliability coefficient of the instrument was 0.74 which was deemed reliable. Descriptive statistical tools were used to analyse the data. The study revealed that there are several motivational packages available to lecturers in Technical Universities. However, these lecturers were not satisfied with them, especially extrinsic motivators such as salary, accommodation and other fringe benefits. The findings further showed that most lecturers were motivated periodically and in some cases annually. The study recommended that management of the four selected Technical Universities should take a serious look at the motivation packages such as working conditions, job recognition, salary, and accommodation facilities since these packages makes them more satisfied. Keywords: job satisfaction, lecturers, motivation, Technical Universities, employees

Examining the Perceptions of Ghanaian Basic School (K-9) Teachers Towards Continuous Professional Development

This study examined the perceptions of Basic School (K-9) Teachers in Greater Accra towards continuous professional development programs. In carrying out this research, a descriptive survey design was applied. A survey was designed with Google Forms, and the link was posted to a WhatsApp group of 141 teachers from 63 basic schools in the Greater Accra Region of Ghana who were purposively sampled to participate in the study. All 141 teachers responded to the survey questions.The findings revealed mixed reactions from teachers towards continuous professional development programs/activities in Ghana. Some professional development programs, for instance, “Cluster/School Based INSET, ICT Integration in Teaching and Learning, Peer Class Observation, Classroom Management, and Subject Content and Methodology Professional Development” activities geared toward the needs of teachers therefore effective, whereas “Educational Leadership and School Management, Education of persons with Special Needs, Micro Teaching, and Social Dialogue” activities were not geared towards teachers needs therefore ineffective. The findings of this study provide valuable information to policymakers, Educational Administrators, and all stakeholders in Education. Considering the study's findings, conclusions and suggestions were provided. Keywords: continuous professional development, teachers’ perception, basic education (K-9) DOI: 10.7176/JEP/14-30-05 Publication date:October 31st 202