429 research outputs found
Transition of hemoglobin between two tertiary conformations: The transition constant differs significantly for the major and minor hemoglobins of the Japanese quail (Cortunix cortunix japonica)
We demonstrate that 5,5âČ-dithiobis(2-nitrobenzoate) â DTNB â reacts with only CysF9[93]ÎČ and CysB5[23]ÎČ among the multiple sulfhydryl groups of the major and minor hemoglobins of the Japanese quail (Cortunix cortunix japonica). Kequ, the equilibrium constant for the reaction,
does not differ very significantly between the two hemoglobins. It decreases 430-fold between pHâ5.6 and pHâ9: from a mean of 7±1 to a mean of 0.016±0.003. Quantitative analyses of the Kequ data based on published X-ray and temperature-jump evidence for a tertiary structure
transition in liganded hemoglobin enable the calculation of Krt, the equilibrium constant for the râât tertiary structure transition. Krt differs significantly between the two hemoglobins: 0.744±0.04 for the major, 0.401±0.01 for the minor hemoglobin. The mean pKas of the two groups
whose ionizations are coupled to the DTNB reaction are about the same as previously reported for mammalian hemoglobins
Effect of cold temperature storage on the quality attributes of pawpaw and guava leathers
The effect of cold temperature storage on the quality attributes of pawpaw and guava leathers was evaluated. Pawpaw leather was significantly higher than guava leather in calorific content, water activity, pH and total mould count throughout the duration of storage. However Guava leather was higher in texture. Sensory scores in relation to period of storage showed that Guava leather gave better result in overall acceptability at zero, one and two months of storage at 8 ± 10C. Guava leather also gave better sensory qualities in fruitiness, smell, chewiness, toughness, colour, and overall acceptability when varietal influence is considered. Guava leather is better accepted.
(African Journal of Biotechnology: 2002 1(2): 61-63
Dynamic Performance Analysis of Cogeneration Potential in Photovoltaic Power System.
The solar cell junction is susceptible to performance degradation, due to internal temperature rise which is further perturbed by ambient temperature rise. The conversion efficiency of the solar module remarkably drops because of temperature rise. The diurnal module temperature hovers above 60 degrees C. It is possible to keep the conversion efficiency high by water-cooled or air blast equipment. This project is a preliminary study of the impact of temperature variation across seasons on the dynamic performance of photovoltaic power system. The photovoltaic (PV) module was mounted on a test rig at latitude 7 degree on top of physics building Obafemi Awolowo University campus. The output voltage of the PV module was applied to a resistive load and system efficiency performance measured over a period of time covering the dry and rainy seasons. Measurements of ambient temperature, PV junction operating temperature, wind speed, solar irradiance, and power delivered were carried out. A numerical algorithm was developed to analyse the data. The transport medium can store heat energy from the solar module, so that a large amount of hot water can be produced. The results show that this thermal transfer benefit, positions the PV system in good stead, for Microgrid: Cogeneration Energy Efficiency functionality. Keywords: Conversion efficiency, Photovoltaic power system, PV module, Water-cooled equipment, Cogeneration
Photovoltaic Generating System Parameter Sizing for Building
Small to medium sized battery storage required to address the intermittency challenge of the energy of solar radiation could be achieved by appropriate sizing of the photovoltaic system parameters like photovoltaic module (PVM) number and battery capacity. This paper presents the results of evaluation of the optimum parameter values in sizing of stand-alone photovoltaic (PV) system that satisfies building energy demand, with almost zero Loss of Power Supply Probability (LPSP). A time step simulation of system performance based on energy balance for various combinations of PV numbers and battery capacities was employed. (Three seasons of operation were considered; rainy, hot and hot/dry). The rainy season result indicating high storage capacity requirement of about (2500-Ah), is of highest cost compared to other seasons. Stand-alone photovoltaic system size that will assuage the intermittency challenge; mitigate peak demand costs and provide near zero LPSP was determined. Keywords: loss of power supply probability, photovoltaic, energy demand, parameter sizing, stand-alon
PERFORMANCE EVALUATION OF TROPICAL BIOFUELLED FISH SMOKING STRUCTURES
Environmental and hygienic concerns associated with traditional fish smoking structures restrict the sale and consumption of smoked products to local markets. This study evaluated the performance of three(improved kiln oven (IKO), mud-type ovens (MTO) and extended drum ovens (EDO)) locally available Biofuelledfish smoking structures and proposed modifications to improve product quality.Three groups of prepared freshwater catfish (Clarias gariepinus) with average live weights of 1.93 kg±46 g, 1.92 kg±50 g and 1.86 kg±50 g was used as test samples. Smoking profiles, final moisture content (FMC), smoking time, smoking temperatures, percentage weight loss (WL) and organoleptic evaluation (ORE) were the performance indicators used during evaluatio
Ethno-religious voting in Nigeria: interrogating voting patterns in the 2019 presidential election
This article analyses voting patterns in Nigeriaâs 2019 presidential election. Its main objective is to gauge continuity or change in ethnic, regional and religious voting in Nigeriaâs elections. The paper takes a historical approach in examining voting patterns in the past elections as a background to the examination of the 2019 presidential election. It was discovered that ethnic, regional and religious sentiments were still major factors that shaped voting choice in the election
Incentive Package, Employeeâs Productivity and Performance of Real Estate Firms in Nigeria
The level of motivation received by an employee as reflected in the satisfaction with the base pay package and other incentives goes a long way to influencing the employeesâ attitude to work, loyalty, performance and job satisfaction. Employeeâs motivation and organization performance has been investigated across different fields and economic sectors. This study takes it further by examining incentive package, employees and organization productivity in real estate firms in Nigeria. Panel survey approach was adopted and three questionnaires administered in each of the one hundred and seventeen (117) estate firms in Ikeja, Victoria Island and Lekki Area of Lagos State. Respondents were two employees and one other in employersâ/management capacity. Descriptive tools such as frequency and percentage were used to identify and determine the proportion of firms that make use of incentive package/option while a 5-point Likert scale and ranking were used to determine and rank the options in order of importance among these firms. Panel data regression model was used to determine the strength of relationship between firmsâ performance/productivity and incentives whilst holding other factors constant. Findings showed amongst others that there is strong positive correlation between incentive and employee productivity, employees are largely dissatisfied with the incentives offered by majority of estate firms and that incentive package is not the most important determinants of performance in real estate firms. The study therefore concludes that employers in real estate firms pay attention to other factors identified and review remuneration and incentive package to boost the morale of their employees for better performance
Aluminum Silicon Carbide Particulate Metal Matrix Composite Development Via Stir Casting Processing
In this paper, conventional simple methods of
producing MMC with attained properties through the dispersion
of silicon carbide in the matrix are investigated. To
achieve these objectives a two-step mixing method of stir
casting technique was employed. Aluminum (99.66 %C.P)
and SiC (320 and 1200 grits) were chosen as matrix
and reinforcement materials respectively. Experiments were
conducted by varying the weight fraction of SiC for 2.5 %,
5.0 %. 7.5 % and 10 %. The result indicated that the
st ir casting method was quite successful to obtain uniform
dispersion of reinforcement in the matrix. This was
evident by the improvement of properties of composites
over the base metal. Reinforced Aluminum Silicon Carbide
(ASC) showed an increase in Young's modulus (E) and
hardness above the unreinforced case and marginal reduction
of electrical conductivity was recorded for the composites.
The silicon carbide of 1200gnts (3 J.lm) showed
increased Young's modulus (E) and hardness of 15 17.6 Mpa
and 26.1Hv values at 7.5% volume fraction silicon carbide;
when compared with the silicon carbide 320 grit (29 J.lm). Also; the electrical conductivity properties of the two grit
sizes of the silicon carbides were less than the base metal
for all the volume fractions of silicon carbide
Crystalline Maculopathy: A Report of Two Patients in Ibadan, Southwestern Nigeria
We present two patients with crystalline maculopathy seen at the Eye Clinic of the University College Hospital, Ibadan, Nigeria. Both patients had diabetes, with the first patient having systemic hypertension controlled on medications. There was no history of kola nut ingestion in the two patients. Medical examination by the internist revealed no other systemic disease. The central vision was good in both patients. Optical coherence tomography localized the crystals to the inner retina, and there was no associated macular edema. Some pathogenetic mechanisms are proffered based on available literature
Aluminum Silicon Carbide Particulate Metal Matrix Composite Development Via Stir Casting Processing
In this paper, conventional simple methods of
Q1
producing MMC with attained properties through the dis
persion of silicon carbide in the matrix were investi11
gated. To achieve these objectives two step-mixing method
of stir casting technique has been employed. Aluminum
(99.66 %C.P) and SiC (320 and 1200 grits) were chosen
as matrix and reinforcement materials respectively. Exper
iments were conducted by varying weight fraction of SiC
for 2.5 %, 5.0 %, 7.5 % and 10 %. The result indicated
that the stir casting method was quite successful to obtain
uniform dispersion of reinforcement in the matrix. This
was evident by the improvement properties of composites
over the base metal. Reinforced Aluminium Silicon Car
bide (ASC) showed increase in Youngâs Modulus (E) and
hardness above the unreinforced case and marginal reduc
tion of electrical conductivity was recorded for the com
posites. The silicon carbide of 1200 grits (3 ÎŒm) showed
increased YoungâsModulus (E) and hardness of 1517.6Mpa
and 26.1 Hv values at 7.5% volume fraction silicon carbidewhen compared with the silicon carbide 320 grit (29 ÎŒm)Also; the electrical conductivity properties of the two grit
sizes of the Silicon Carbides were less than the base metal
for all the volume fraction of Silicon Carbid
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