Thermoelectric Amplification of Phonons in Graphene

Amplification of acoustic phonons due to an external temperature gredient ($\nabla T$) in Graphene was studied theoretically. The threshold temperature gradient $(\nabla T)_0^{g}$ at which absorption switches over to amplification in Graphene was evaluated at various frequencies $\omega_q$ and temperatures $T$. For $T = 77K$ and frequency $\omega_q = 12THz$, $(\nabla T)_0^{g} = 0.37Km^{-1}$. The calculation was done in the regime at $ql >> 1$. The dependence of the normalized ($\Gamma/\Gamma_0$) on the frequency $\omega_q$ and the temperature gradient $(\nabla T/T)$ are evaluated numerically and presented graphically. The calculated $(\nabla T)_0^{g}$ for Graphene is lower than that obtained for homogeneous semiconductors ($n-InSb$) $(\nabla T)_0^{hom} \approx 10^3Kcm^{-1}$, Superlattices $(\nabla T)_0^{SL} = 384Kcm^{-1}$, Cylindrical Quantum Wire $(\nabla T)_0^{cqw} \approx 10^2Kcm^{-1}$. This makes Graphene a much better material for thermoelectric phonon amplifier.Comment: 12 Pages, 6 figure

The quality of locally-manufactured cornmill grinding plates

Maize was milled either ‘wet’ or ‘‘dry’’ using locally-manufactured milling plates. Samples of milled maize were taken and analyzed for elemental iron (Fe). Results show that iron particles from milling plates contaminates the milled maize and that the level of contamination increases with the quantity of milled maize. This is the case in both ‘wet’ and ‘dry’ milling. However, the relationship between the mass of elemental iron (Fe) in milled maize and mass of milled maize in ‘wet’ milling differed from that of ‘dry’ milling. That is, in ‘dry’ milling the rate of metal loss decreases at first and then increases with mass of milled maize, whereas in ‘wet’ milling, the rate increases monotonically with mass of milled maize. The difference could be explained in terms of the mechanism(s) or mode(s) of metal loss under the different milling conditions. In ‘dry’ milling, loss of metal is initially controlled by friction wear and later by erosion-corrosion. In the case of ‘wet’ milling metal loss could be attributed to conjoint action of corrosion and friction wear. The implications of these results are briefly discussed in terms of the possible health effects on consumers of foods prepared from such contaminated milled maize

Biosand Filtration as a Green Approach to Septic Tank Effluent Management in a Tertiary Institution in Ghana

Sewage and household effluents at some institutions in Ghana have been discharged into the ocean for years. Thisdegrades environmental media and is detrimental to ecological systems. The Three Local Plastic Barrel-Biosand Filter (TLPB-BSF) is an innovation on the slow sand filter that has been used to prevent discharge of raw sewage into the environment. The study aimed to test the performance of a modified BSF on sewage tank effluent and assess suitability of the filtrate for non-drinking purposes at a tertiary institution renamed KOTU to maintain confidentiality. Method: A filtration system made of three modified interconnected BSF was constructed on-site, with last filter connected to a storage tank. The modification was the provision of an additional media (charcoal) in the second barrel. Two sample collections were made from the system one week apart. The pre-filtrate samples were raw septic tank effluent (STE) and the samples obtained after running system was Biosand filter effluent (BSFE). Samples were analysed for physical and microbiological parameters at designated laboratories. Measured values of the parameters in pre-filtrate and filtrate samples were compared with EPA (Ghana) reference values. The removal efficiency of a parameter was computed as the difference between pre-filtrate and filtrate values expressed as a percentage of the pre-filtrate value. Results: Most of the effluent parameters from the BSF were within the EPA standards, while others were unacceptable. Removal efficiencies obtained for the parameters were: Ni trogen (83.3%), Phosphorus (89.5%), Total Suspended Solids (71.3%), Total Dissolved Solids (66.2%), Total coliform (99.9%), Faecal coliform (99.7%) and E. coli (97.6%). Conclusion: BSF is effective for upgrading physical and microbial quality of sewage at household and institutional level, prior to discharge in the environment. It produced a filtrate that met most of EPA standards for irrigation of non-edible crops

Potential impact of large scale abstraction on the quality of shallow groundwater for irrigation in the Keta Strip, Ghana

The potential impact of large-scale groundwater abstraction on the shallow groundwater and crop production within the Keta Strip was examined. The assessment was based on geophysical data, data on groundwater quality, soils, irrigation water requirement and hydrogeology of the Strip. The results indicate that the shallow groundwater can support only medium to high salt tolerant crops. This is consistent with the medium salt tolerant crops especially shallot and onion currently grown in the area. Large-scale irrigation of the Strip will require at least 2 x 107 m3 of water during the dry season. Abstraction of such large volume of water from the shallow aquifer will result in the lowering of water table by approximately 1.0 m per year. The consequence of this will be the up coning of the fresh/saline water interface probably by as much as 4.7 m, resulting in salinisation of the fresh water lenses particularly around the lagoon end where most of the shallot farms are situated. Apart from up conning, salinisation may result from ingress of brackish/saline water from the lagoon and sea into the fresh water lenses. Though post irrigation rainfall will be adequate to nullify the water table depression, once the fresh water is contaminated, it is extremely difficult to decontaminate. Consequently, the shallow groundwater will evolve from medium through high to very high salinity hazard to crops. Specific ions toxicity will also increase due to increment in the concentrations of individual ions. Thus, the previously freshwater will become unsuitable for the production of even high salt tolerance crops. This will effectively halt the lucrative shallot and other vegetable farming in the Keta Strip and thus signify socio-economic disaster for the Keta Strip in particular and Ghana in general

A Factor Analysis of Consumer’s Buying Behavior of Sanitary Pads

The purpose of this research is to investigate into what factors influence the buying behaviour of consumers of sanitary pads in Takoradi Polytechnic. Consumer behaviour has been changed dramatically in the past decade. In today’s world of growing competition where there are numerous brands selling the same products, consumers is having an abundant number of choices and many other factors influence their buying behaviour. In order to accomplish this objective of the study, a sample of five hundred (500) consumers were sampled from both female (staff and student) of the Polytechnic community. A ten item questionnaire that employs a five-point differential scale ranging from ‘strongly disagree’ to ‘strongly agree’ was administered to the respondent. Among other things, the study result reveal that there are four dimensional factors informing the purchasing behaviour of consumers of sanitary pads, which accounted for 65.3% of variance in the original variables. Using factor analysis via principal component factoring with resulting data analysis done in SPSS (16), the dimensions adduced to be influencing buying behaviour of sanitary pads were: Health features (factor 1), Product features (factor 2), and Social influence (factor 3) and Economic factors( factor 4). This study is useful to the marketers as they can create various marketing programme that they believe will be of interest to the consumers. It can also boost their marketing strategy and also help other people who are working in other industries or in any private sector organization. Keywords: Consumer Buying Behaviour, Sanitary pads, Factor analysis, Principal Component Factoring

Phytochemical Analysis of Medicinal Plants Used for the Management of Hypertension by Esan people of Edo State, Nigeria

Hypertension is one of the principal health problems in the society and a leading cause of cardio-vascular deaths in various communities worldwide. Over 33 plants and their products have been reported in Nigeria and other West African countries to offer remedies for the management of hypertension. In Esanland of Edo State, Nigeria, 14 endemic plant species distributed in 12 taxonomic families have been identified by various traditional health practitioners as being effective and commonly used to manage hypertension (Psidium guajava, Piper guineense, Loranthus spectobulus, Talinum triangulare, Senna occidentalis, Rauwolfia vomitoria, Allium sativum, Allium cepa, Carica papaya, Euphorbia hirta, Ocimum gratissimum, Persea americana, Peperomia pellucida, and Vernonia amygdalina). Qualitative phytochemical analyses of the plant parts have revealed the presence of various components of medical importance including tannins, flavonoids, cardiac glycosides, alkaloids, saponin and inulins. Cardiac glycosides were present in all the species studied while alkaloids were present in all except A. sativum, A. cepa, O. gratissimum and P. americana. Saponnins were present in all except the seeds of negro coffee (S. accidentalis), while tannins were present in all except bulbs of garlic (A. sativum). This preliminary study draws attention to the need for further studies of the active principles identified in the reported species for the treatment of hypertension in Esanland in order to understand their mode of action in controlling hypertension

SOLAR DRYER WITH BIOMASS BACKUP HEATER FOR DRYING FRUITS: DEVELOPMENT AND PERFORMANCE ANALYSIS

Most solar dryers rely on only solar energy as the heat source. This condition limits its use in off -sunny periods such as cloudy, rainy seasons and after sunset. The objectives of this study were to: develop a solar dryer with biomass backup heater for drying fruits; analyze its performance; and carry out comparative analysis of the dryer with and without biomass backup heater. An indirect solar dryer was designed, constructed and analysed using 4mm slices of pineapples and mangoes. Temperature, humidity and ambient air temperature were measured using Tinytag data loggers, EasyLog – USB 2 and HI 91610C Thermo-hygrometer. A 300g weight of charcoal, costing GHC 0.5 (US$0.16)was fed into the backup heater every 1-2 hours with a running cost of US$ 1-2.88/day. The results showed that the moisture content (MC) of the pineapples reduced from 87% to 16%(wb) and that of mangoes reduced from 85% to 15.5% (wb). On average, solardrying with backup took 14-18 sunshine hours to attain the desired MC, while that without backup took 20-27 sunshine hours. With biomass backup heater the drying rates were: pineapples (32.5g/h) and mangoes (19.3g/h), while without backup the drying rates were: pineapples (23.7g/h) and mangoes (15.5g/h). Better performance was obtained when the dryer was with a biomass backup heater.Keywords: Moisture; dryer; temperature; solar; biomas

Bridging the Gap between Rural Water Supply and Demand using Harvestable Rainwater: A Case Study of Adansi-Fumso

Rainwater harvesting has several benefits including providing a valuable alternative source of water for households, reduction in flood flow to storm drains and settlement erosion as well as health benefits. The research aimed at assessing and confirming the available renewal water sources, determining the cost of developing a rainwater harvesting system and assessing the potential of rainwater as a supplement to water supply at Fumso. Using a systematic random sampling technique and a sample size of 100 respondents, it was discovered that rainwater harvesting in Adansi Fumso has the potential to conserve on-site potable water use, protect water quality and reduce the risk of flooding within the community. Rainwater was preferred by the community due to its easy accessibility, nature (clean, pure, healthier and tastier), cost and quality. An examination of the rainfall records at AngloGold Ashanti weather station at Obuasi revealed an average annual rainfall of 1449.2 mm with the drier months (November, December, January and February) receiving only a quarter of the average monthly rainfall. The relatively high rainfall means that rainwater harvesting system designs need to be taken as a priority in addressing the water shortage situation in the community. Geometrically uniform building shapes and the local hydrology can provide sufficient rainwater to serve buildings in the community. The cost of the proposed rainwater harvesting system is GH ¢ 389.00 ($256.00). Reasons have been given for the need for this project and recommendations made for its implementation at Adansi Fumso as the best alternative source of water to the fewer boreholes in the community