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

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

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

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

Occurrence of entomopathogenic nematodes (Steinernematidae, heterorhabditidae) as potential biocontrol agents against Spodoptera frugiperda infesting Zea mays

Synthetic insecticides are used worldwide to manage invasive fall armyworm (Spodoptera frugiperda) in cereals, in spite of the chemical’s prohibitive cost and threats to environmental health. In Ghana, little attention has been given to entomopathogenic nematodes as insect pest biocontrol agents, due to the existence of dismal expertise in the field. This study evaluated maize (Zea mays L.) farms for endemic entomopathogenic nematodes as potential biological control agents against fall armyworms infesting maize in Ghana. Entomopathogenic nematode juveniles were extracted using an insect baiting technique, White traps. These Rhabditid nematodes (Heterorhabditis; Steinernema) were found in 75% of 200 soil samples; and 92.5% of 40 districts targeted by this study. The Greater Accra region recorded the greatest population density (1,820 juveniles per 5 fall armyworm larvae cadavers); while; the Central region recorded the lowest density (81 juveniles per 5 fall armyworm larvae cadavers). There was high presence of entomopathogenic nematodes across the study areas. Therefore, entomopathogenic nematodes offer a promising alternative strategy for managing fall armyworm infestation of maize in Ghana to minimise over-reliance on synthetic insecticides. &nbsp

Assessing arthropod pests and disease occurrence in cassava (Manihot esculenta Crantz) and cowpea (Vigna unguiculata L. Walp) intercropping system in the Ashanti Region, Ghana

On-station trials were conducted at CSIR-Crops Research Institute’s research farms at Kwadaso and Ejura, Ashanti Region, Ghana, during 2010/2011 cropping season, to assess the pests and disease occurrence in cassava-cowpea intercrop farming systems and their effect on yield of produce. Three improved cassava varieties and a local variety were intercropped with an improved cowpea variety, and cowpea only constituted the treatments. Abundance of Bemisia tabaci was comparable between sole cassava and cassava-cowpea intercrop, but was significantly less on the sole cowpea. The incidence and severity of cassava mosaic disease was higher on the local variety than on the improved varieties. Root yield of cassava did not differ between sole and intercropped cassava with cowpea. However, Kwadaso had higher root yield than Ejura. Dry grain yield of cowpea was similar at Kwadaso and Ejura for both sole and intercrop scenarios. This baseline information will be useful on disease and pests incidence in sole crop and cassava-cowpea intercropping system

The utilization of positron emission tomography in the evaluation of renal health and disease

Purpose: Positron emission tomography (PET) is a nuclear imaging technique that uses radiotracers to visualize metabolic processes of interest across different organs, to diagnose and manage diseases, and monitor therapeutic response. This systematic review aimed to characterize the value of PET for the assessment of renal metabolism and function in subjects with non-oncological metabolic disorders. Methods: This review was conducted and reported in accordance with the PRISMA statement. Research articles reporting “kidney” or “renal” metabolism evaluated with PET imaging between 1980 and 2021 were systematically searched in Medline/PubMed, Science Direct, and the Cochrane Library. Search results were exported and stored in RefWorks, the duplicates were removed, and eligible studies were identified, evaluated, and summarized. Results: Thirty reports met the inclusion criteria. The majority of the studies were prospective (73.33%, n = 22) in nature. The most utilized PET radiotracers were 15O-labeled radio water (H215O, n = 14) and 18F-fluorodeoxyglucose (18F-FDG, n = 8). Other radiotracers used in at least one study were 14(R,S)-(18)F-fluoro-6-thia-heptadecanoic acid (18F-FTHA), 18F-Sodium Fluoride (18F-NaF), 11C-acetate, 68-Gallium (68Ga), 13N-ammonia (13N-NH3), Rubidium-82 (82Rb), radiolabeled cationic ferritin (RadioCF), 11C‐para-aminobenzoic acid (11C-PABA), Gallium-68 pentixafor (68Ga-Pentixafor), 2-deoxy-2-F-fluoro-d-sorbitol (F-FDS) and 55Co-ethylene diamine tetra acetic acid (55Co-EDTA). Conclusion: PET imaging provides an effective modality for evaluating a range of metabolic functions including glucose and fatty acid uptake, oxygen consumption and renal perfusion. Multiple positron emitting radiolabeled racers can be used for renal imaging in clinical settings. PET imaging thus holds the potential to improve the diagnosis of renal disorders, and to monitor disease progression and treatment response