Reliability - Based Design of Reinforced Concrete Two-Way Solid Slabs Using Eurocode 2

In this work, a FORTRAN-based computer program was developed to aid the design of reinforced concrete slabs to Eurocode 2 (EC 2)[1]design requirements at constant reliability levels using First Order Reliability Method (FORM).The design variables for the design of the slab were considered random with safety indices calculated using FORM. It was shown among other findings that the FORM design procedure gave more economical designs considering the area of steel required and final depth of section, than the EC 2 design procedure when a target safety level of 3.0 was considered. Also, example of design using the program was included for various values of target safety indices at constant geometrical, loading and end condition of the slab. The developed program is therefore suitable for application.http://dx.doi.org/10.4314/njt.v33i4.

INDUCTION OF NORMOCYTIC-NORMOCHROMIC ANAEMIA IN Clarias gariepinus (Burchell, 1822) EXPOSED TO ACUTE CONCENTRATION OF 1, 1-dimethyl 4,4-bipiridillium (PARAQUAT) UNDER LABORATORY CONDITIONS

fish were exposed to test water separately diluted with acute concentrations of paraquat of 0, 15, 20, 25 and 30mg/L. A 96Hrs exposure to acute concentrations of the toxicant resulted in normocytic-normochromic anaemia in the exposed fish. Blood indices attributable to normocytic-normochromic anaemia was observed with a significant (p<0.05) decrease in haemoglobin, haematocrit, red blood cells compared with fish in the control test: Mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscularhaemoglobin concentration (MCHC) were not significantly different (p>0.05). White blood cells, lymphocytes, monocytes, Neutrophils, eosinophil and basophil were also not significantly different (p>0.05) with increasing concentrations of the toxicant&nbsp

Trend of neonatal mortality in Nigeria from 1990 to 2017 using time series analysis

The study examined the incidence of the rate of Neonatal Mortality in Nigeria. The incidence tested with use of Time Series Analysis (ARIMA). The trend plot of the incidence shows that there has been steady decrease in the incidence rate over the years. The series was stationarity using the Augmented Dickey-Fuller (ADF) Test, the result found to be stationary. The Correlogram of the incidence also supports the stationarity of the series at 1% level of  significance. The model that best describes the incidence was tested using the Box-Jenkins four step procedures, which involve identification, explanation, diagnostic and forecasting. ARMA (1, 1), and ARIMA (1, 1, 1) models were tested, and ARIMA (1, 1, 1) model happens to be the best model that best fits the series. The time series analysis shows that neonatal mortality rate has reduced by 17.8% from 51. 7% in the year 1990 to 33. 9% in the year 2017.Keywords: Auto regression, Moving average, Mortality, Stationarity, Correlogra

Evaluation of Teachers’ Activitties in the use of Animated Instrustional Resourse Materials in Biology Teaching in Senior Secondary Schools in Bauchi State Nigeria

This paper presents a profile on how teachers in senior secondary schools in Bauchi state Nigeria utilise animated instructional resource (AIR) in the teaching of biology. A structured questioner used to generate data on the availability, accessibility and application of the AIR for classroom instruction by teachers.  The instrument for data collection was piloted in the three senatorial zones, which include Bauchi, Ningi and Katagum zones. The result indicated low awareness of biology teachers to the existence of AIR in senior secondary schools. Analysis of availability and utilization of animated instructional resource by teachers showed sharp contrast between the affirmative and the null, 3% shows ‘yes’ while 97% was ‘no’, indicating that there is no availability and utilization of AIR in senior secondary school. With regards to teachers’ opinion on the need for AIR in schools, the teachers’ overwhelmingly indicated great need. However 100% voted in favour of the need for the package. The teachers also indicated willingness to buy AIR if sold, because AIR is found to be very useful in classroom instruction

EXPLORING THE INAR MODEL ON HEAVY TAILED TIME SERIES DATA WITH OUTLIERS

Count data are intrinsically measures of event frequency; it is clear that there is an intrinsic relationship with recurring time to event. Events are typically tallied within time intervals for practical and convenient reasons. The existence of outliers is one issue that prevents count data from being stationary in time series analysis; this has an impact on the effectiveness of fitting several common stationary models to the count data collected over time. Thus, the purpose of this study was to examine how well the Integer Valued Autoregressive (INAR) model performed while modeling count data that included outliers. While this model has been studied for count time series data, it has not been studied for varying degrees of outliers. A monte-carlo simulation was carried out to select the best INAR(p), where p=1,2,3 and 4 on data with 10%, 20% and 30% outliers at different sample sizes. The INAR (4) has the best fit across the sample sizes at the larger percentages of outliers while INAR (3) at the lowest percentage with smallest information criteria of assessment and they are therefore recommended for such modeling.

Effect of Nanosilica on Mechanical and Microstructural Properties of Cement Mortar

Recently, nanomaterials (such as nanosilica) are receiving special attention because of their ability to improve the performance of concrete compared with traditional mineral admixtures. In this work, a number of specimens were prepared to study the behavior of cement mortar containing nanosilica. The cement replacement by nanosilica of 3% and 5% by weight of cement was used. The mechanical and microstructural properties of the specimens were investigated. An experimental result from literature was utilized to predict the transport of chloride into reinforced concrete structures modified with nanosilica using COMSOL multiphysics commercial package. The experimental results show that cement mortars containing nanosilica have higher strength than ordinary portland cement mortars. Also, the SEM images confirmed the improvement in the microstructure of mortar with nanosilica

INDUCTION OF MICROCYTIC-HYPOCHROMIC ANAEMIA IN Clarias gariepinus (BURCHELL, 1822) EXPOSED TO SUB-LETHAL CONCENTRATIONS OF 1, 1-DIMETHYL 4, 4-BIPIRIDILLIUM DICHLORIDE (PARAQUAT) UNDER LABPRATORY CONDITIONS

Microcytic-hypochromic anaemia was induced in Clarias gariepinus (Burchell, 1822) at intervals of 1, 7 and 14 days. Experimental fish were exposed to test water separately diluted with sub-lethal concentrations of paraquat of 0, 0.06, 0.07, 0.09 and 0.12mg/L. 14 days’ exposure to the sub-lethal concentrations of the toxicant resulted in mirocytic-hypochromic anaemia in the exposed fish. Blood indices attributable to mirocytichypochromic anaemia was observed with a significant (p<0.05) decrease in haemoglobin, haematocrit, redblood cells, Mean corpuscular volume (MVC), Mean corpuscular haemoglobin (MCH), Mean corpuscular haemoglobin concentration (MCHC), white blood cells, lymphocytes, monocytes, Neutrophils and eosinophil compared with the fish in the control test.&nbsp

Effect of Neem Seed Husk Ash on Concrete Strength Properties

Neem Seed Husk is a by-product obtained during industrial processing of Neem Seed to extract oil and produce fertilizer. Laboratory tests on Neem seed husk ash (NSHA) mixed with cement were conducted to find its effect on concrete strength and workability. Tests including slump test, compressive strength test, concrete density test and scanning electron microscope (SEM) were carried out on concrete partially replaced with 0%, 5%, 10%, 15%, 20% and 25%NSHA and presented. The test results indicate that concrete workability is affected by NSHA partial replacement by increase in the slump at 5% and 10% replacements. But it decreases the slump at 15%, 20% and 25% replacements. At 28 days curing, only the control (0% replacement) and 5% replacement satisfied the target compressive strength and therefore can be used for non-structural and mass concrete applications. Densities of most of the cubes partially replaced with NSHA are generally higher than that of the control concrete; this is further supported by the SEM. which indicates that NSHA act as filler and occupy the voids between the aggregates, thereby making the concrete more compact and having higher densities. All the samples have satisfied the density requirement of British standard for normal- weight concretehttp://dx.doi.org/10.4314/njt.v33i2.

Cytotoxicity and antibacterial activity of fruits extracts of Xylopia aethiopica against some selected beta-lactamase producing bacteria

Xylopia aethiopica commonly known as the West African pepper tree is consumed as food condiment and also used traditionally in the treatment of cough, bronchitis, dysentery and female sterility. Air-dried and ground fruits of Xylopia aethiopica were extracted using ethanol and the recovered extract was partitioned to give chloroform, water, methanol and n-hexane fractions. The five extracts were screened for antibacterial activity against strains of β-lactamase producing bacteria: Escherichia coli, Proteus sp., and Klebsiella pneumonia as well as cytotoxicity against brine shrimp larvae. The result of the antibacterial screening showed that all the extracts exhibited selective activity against Proteus sp., the interface-2 demonstrated the highest activity with diameter of zone of inhibition of 14mm at 1000μg/disc. On the other hand, methanolic extract showed high cytotoxic activity in the brine shrimp lethality bioassay with LC50 value of 3.4μg/mland moderate antibacterial activity with diameter of zone of inhibition of 12mm at 1000μg/ml.Keywords: Xylopiaaethiopica; Extracts; antibacterial activity; β-lactamase producing bacteria; cytotoxicity; brine shrimp lethality bioassa