Proximate, caffeine and tannin analyses in some brands of tea consumed in Kano Metropolis, Nigeria

The determination of proximate, caffeine and tannin contents of five different (China, Kenya, India, Srilanka and Mambilla) tea leaves samples sold in Kano markets was conducted. The moisture content was generally high in all the tea samples and ranged from 5.6% in Mambila to 7.5% in India samples. Ash content was relatively low and ranged between 4.90% in Srilanka to 7.20% in Mambila and Kenya samples respectively. Crude fibre ranged from 14.00% in China to 18.82% in Srilanka samples, while ether extract content was within the range of 9.30% to 10.60% with the highest value found in Mambila sample and the least value in Kenya sample. Total nitrogen contents were low when compared with other workers’ results and ranged from 0.88% in Kenya to 1.75% in Mambila and Srilanka samples respectively. Caffeine and tannin contents were found to be 1.4% in Kenya to 2.80% in China, 6.00% in Mambilla to 7.80% in India samples respectively. Keywords: Proximate, Analysis, Caffeine, Tannin, Tea, Kan

Analysis of some metals in some brands of tea sold in Kano, Nigeria

Tea leaves can be a source of mineral components and trace elements as well as some undesirable substances due to exposure to the environment. In this study, Mg, Fe, Ca, Zn, Mn, Cu and Pb were analyzed by Atomic Absorption spectrophotometer (AAS), K and Na were also determined by flame photometer. Among the metals analyzed, K was the most abundant, ranging from 30.00mg/dm3 in china sample to 34.60 mg/dm3 in Srilanka sample, followed by Mg with 9.03 mg/dm3 in India sample to 9.21 mg/dm3 in Srilanka sample. Ca, Mn, Fe, Zn, Na and Cu were also found in reasonable amounts. Fortunately, toxic heavy metal (Pb) had the lowest concentration in all the tea samples with concentration ranging from 0.04 mg/dm3 in India and Srilanka samples to 0.09 mg/dm3 in China sample. Keywords: Essential metals, Trace metals, Tea, Kan

In vitro shoot multiplication of Ziziphus spina-christi by shoot tip culture

In vitro shoot multiplications were obtained successfully from shoot tips of Ziziphus spina-christi by placing explants into solidified medium (MS medium) supplemented with 0.01 mg/l NAA and 0.1 mg/l BA or 0.1 mg/l IAA and 1.0 mg/l kinetin. It was concluded that lower concentrations of all cytokinin studied were better for lateral bud proliferation and that BA and 2IP were better than kinetin in the production of lateral branches. No growth regulators were required for shoot growth and elongation. The shoots rooted best on MS medium supplemented with 1.0 mg/l IBA. Plantlet survival after transfer to soil was more than 90%. The shoot proliferation method described could be used for the mass clonal propagation of selected genotype cv Noaf variety. The variety is in a great demand due to its attractive fruit characteristics such as flavour, sweetness and fruit yield

TECHNO-ECONOMIC INVESTIGATION OF DIFFERENT ALTERNATIVES OF IMPROVING SIMPLE GAS TURBINE INTEGRATION OPTIONS

This study investigated the effect of integrating various models proposed to improve a simple gas turbine power plant. A computer program was developed in Matlab software was used to simulate the performance parameters. The energy and exergy analysis of the plant was carried out. The energy and exergy analysis result revealed that both energy and exergy efficiency of plant is low as a result three improvement options were considered. They include Model 1: reducing inlet air cooling (IAC) of the compressor by using the wasted energy in the natural gas pressure drop station. Model 2: recovering wasted energy in the exhaust through heat recovery steam generator (HRSG) and injecting steam into the combustion chamber and lastly Model 3: by combining the two methods. The result showed that among the three methods of improving the plant investigated Model 3 was found to boost power output of the plant from 28.3 MW to 78.4 MW while the thermal and exergetic efficiency improved by 25.5 and 23.6% respectively. Furthermore, from economic and environmental point of view, the lowest levelized cost of electricity as well as the specific emissions was observed in Model 3. Consequently, Model 3 is selected as the best option in improving the simple gas turbine.  http://dx.doi.org/10.4314/njt.v36i3.2

INVESTIGATION OF FOULING EFFECT ON OVERALL PERFORMANCE OF SHELL AND TUBE HEAT EXCHANGER IN A UREA FERTILIZER PRODUCTION COMPANY IN NIGERIA

Fouling is one of the major problems confronting heat exchangers in most industries. Shell and tube heat exchangers are perhaps the most common types of heat exchangers in industrial applications due to their flexibility and versatility. This study investigated the effect of fouling on the performance of the shell and tube heat exchanger unit of a CO2 fertilizer production company in Nigeria. Two different heat exchanger units (cold gas pre-heater and CO2 water cooler in scrubbing process) were considered for the analysis of this study. Data were obtained from operational log book, periodic maintenance data sheet and vendor’ design data sheet. The data were analyzed using various energy equations encoded in MATLAB to determine the overall heat transfer coefficients, heat duties, capacity ratios and effectiveness. The results obtained from the analysis showed that on average, the deviation of overall heat transfer coefficient, heat duty, and effectiveness from design values were 24.10%, 26.27%, and 17.17% respectively. Fouling factor was 31.58% more than the design value in a period of 47 days of operation. Fouling adversely affects the performance parameters of the heat exchangers. http://dx.doi.org/10.4314/njt.v35i1.2

Obesity and high risk pathological features of papillary thyroid carcinoma: A retrospective analysis of a university hospital in Pakistan

BACKGROUND: Incidence of papillary thyroid carcinoma (PTC) and the frequency of obesity is increasing globally. In literature, relationship between excessive body weight and bad prognostic features of PTC is still debatable. In this study, we aimed to explore the association of obesity with high risk pathological features of PTC in a population treated by total thyroidectomy +/- neck dissection. MATERIALS AND METHODS: Retrospective analysis of patients at Aga Khan University Hospital from January 2013 to December 2014, who underwent total thyroidectomy +/- neck dissection due to PTC. Patients were grouped according to World Health Organization (WHO) classification of BMI. They were categorized into two groups, i.e. normal (BMI= 18.5 - 24.9 kg/m2) and obese (BMI = 30 kg/m2) as none of our patients lie in underweight and overweight category. Pathological features i.e. T-stage, multifocality, bilaterality, extrathyroidal extension, vascular invasion and N-stage were assessed. All tumors were staged according to TNM staging system proposed by 2010 American Joint Committee on Cancer (AJCC). Odds ratio (OR) with 95% confidence interval was used to examine the association between BMI ∧ pathological characteristics of PTC. RESULTS: A total of 53 patients were treated for PTC in two-years period. There were 38 female and 15 male patients. Twenty-eight patients had BMI in normal while twenty-five in obese category. Patients who were in obese category had a significantly greater risk of having a multifocal tumor (OR=5.55, p-value=0.02) and bilaterality (OR=6.54, p-value=0.01) compared to normal weight patients. No positive associations were identified between BMI and extrathyroidal extension, high T-stage, vascular invasion and N-stage. CONCLUSION: Obesity is not associated with high risk pathological features such as extrathyroidal extention, high T-stage, vascular invasion and N-stage in PTC. Although it has been correlated with multifocal and bilateral tumors in this retrospective study, the presence of these factors alone is not adequate to support the association conclusively

Impact analysis of crossovers in a multi-objective evolutionary algorithm

Multi-objective optimization has become mainstream because several real-world problems are naturally posed as a Multi-objective optimization problems (MOPs) in all fields of engineering and science. Usually MOPs consist of more than two conflicting objective functions and that demand trade-off solutions. Multi-objective evolutionary algorithms (MOEAs) are extremely useful and well-suited for solving MOPs due to population based nature. MOEAs evolve its population of solutions in a natural way and searched for compromise solutions in single simulation run unlike traditional methods. These algorithms make use of various intrinsic search operators in efficient manners. In this paper, we experimentally study the impact of different multiple crossovers in multi-objective evolutionary algorithm based on decomposition (MOEA/D) framework and evaluate its performance over test instances of 2009 IEEE congress on evolutionary computation (CEC?09) developed for MOEAs competition. Based on our carried out experiment, we observe that used variation operators are considered to main source to improve the algorithmic performance of MOEA/D for dealing with CEC?09 complicated test problems

Fluvial biotopes influence macroinvertebrate biodiversity in South-East Asian tropical streams

This is the final version. Available from Ecological Society of America via the DOI in this record.Given the widespread degradation of aquatic systems caused by land‐use changes associated with palm oil production in South‐East Asia, it is imperative to identify and study the remaining undisturbed rivers and streams. Stream macroinvertebrates are reliable indicators of environmental health. Linking the community structure of these organisms to natural hydraulic and geomorphic conditions (categorized as biotopes) is vital for the conservation and restoration of streams. This study characterizes the effects of biotopes on macroinvertebrate community structure in three streams within Ulu Temburong National Park in northern Borneo. Biotopes within these streams were categorized as either bedrock (waterfalls and cascades) or mixed substrate (riffles and pools). In total, 119 taxa were collected from all sampled biotopes, but not all taxa were collected from each stream. Biotopes were statistically distinct in terms of taxonomic richness, but not mean individual density or average community biomass. There were differences in community structure between waterfalls, cascades, pools, and riffles. The survey suggests that pool and riffle biotopes were more vulnerable to scouring flows and had similar community structure, while waterfalls and cascades likely experienced lower sheer stress during floods and had similar macroinvertebrate communities. This study has found that classification and mapping of macroinvertebrates with biotope theory in pristine, tropical streams is a useful framework for simplifying the many linkages between ecology, geomorphology, and hydrology. These natural patterns increase our understanding of tropical streams and can be used to assess the impacts of forest degradation.Natural Environment Research Council‐funded PhD Studentshi