Ternary and quaternary blends as partial replacement of cement to produce hollow sandcrete blocks.

Hollow sandcrete blocks constitute more than 90% of residential building construction in developing countries especially in West Africa. Over-reliance on dredged river sands and conventional ordinary Portland cement (OPC) contributes to environmental degradation and post-construction problems such as swelling and shrinkage-induced cracks prevalent in construction projects. The study investigates potential utilization of locally available materials such as laterite, calcite and calcined clay as ternary and quaternary blends to replace cement and quarry dust as 100% replacement of river sand with the aid of Taguchi-Response surface methodology approach. Optimum ternary blend of 24% calcined clay +1% calcite +75% OPC is recommended to achieve volume stability, higher compressive strength and higher flexural load capacity. Alternatively, ternary blends of 24% calcite +4% calcined clay +72% OPC can also be utilized. The improved mechanical properties were attributed to the Na- and Ca-rich aluminosilicates provided by the blended cements. Successful utilization of ternary and quaternary blended cements to produce stronger, durable and eco-friendly sandcrete blocks depends on utilization of high binder-to-aggregate ratio, optimal combination of the constituents, appropriate water-cement ratio and curing/production method. Partial and 100% replacement of river sand with granite dust is possible and contributes to reduction of environmental problems caused by river dredging as well as cleaner, ecofriendly construction. Ternary and quaternary blended cements is recommended to avert post-construction problems such as swelling and shrinkage-induced cracks prevalent in construction projects.

Performance comparison of neural network training algorithms in the modeling properties of steel fiber reinforced concrete.

Our study is aimed at modeling the effect of three contributory factors, namely aspect ratio, water cement ratio and cement content on the water intake/absorption, compressive strength, flexural strength, split tensile strength and slump properties of steel fiber reinforced concrete. Artificial neural network (ANN) as a multilayer perceptron normal feed forward network was integrated to develop a predictive model for the aforementioned properties. Five training algorithms belonging to three classes: gradient descent, Levenberg Marquardt (quasi Newton) and genetic algorithm (GA). The ANN configuration consists of the input layer with three nodes, a single hidden layer of ten nodes of the output layer with five nodes. The study also compared the performance of all algorithms with regards to their predicting abilities. The ANN training was done by splitting the experimental data into the training and testing set. The divergence of the RMSE between the output and target values of the test set was monitored and used as a criterion to stop training. Although the convergence speed of GA was far higher than all other training algorithm, it performed better in predicting the water intake/absorption, split tensile strength and slump properties. However, incremental back propagation (IBP) and batch back propagation (BBP) outperformed GA in predicting the compressive strength and flexural strength respectively. The overall performance of the training algorithm was assessed using the coefficient of determination and the absolute fraction of variance obtained for the test data set and GA was found to have the highest value of 0.94 and 0.92 respectively. In determining the properties fiber reinforced concrete according to GA-ANN implementation, the water/cement ratio played slightly more dominant role than the aspect ratio and this was followed by cement content.

Parameters of thyroid function in the endemic goitre of Akungba and Oke-Agbe villages of Akoko area of southwestern Nigeria.

The parameters of thyroid function were determined in Akungba and Oke-Agbe communities of Akoko area, where goiter is endemic and compared to a control population of Erinmo and Ifewara in Ijesha area, both areas being in southwestern Nigeria. The two study areas have similar physical and geological settings. However, while the main carbohydrate source of the control population are yam and/or bread-fruit, the Akoko population derives her carbohydrates mainly from cassava which could lead to increased serum thiocyanate, a goitrogen. The serum level of tetraiodothyronine (T4) was significantly (P < 0.05) higher in Ifewara (11.0) and Erinmo (11.8) compared to Akungba (7.1) and Oke-Agbe (8.8[symbol: see text]micrograms/dL). The triiodothyronine (T3) was significantly (P < 0.05) higher in Ifewara (193) than Erinmo (133) and also significantly (P < 0.05) higher in Oke-Agbe (127) compared to Akungba (107 mg/dL). Conversely, thyroid stimulating hormone (TSH) (microU/mL) level was significantly (P < 0.05) higher than values obtained from Ifewara (4.5) and Erinmo (3.3). T3/T4 ratio above 25, indicative of hypothyroidism and endemic goiter, was 14, 7, 4 and 0% from Akungba, Oke-Agbe, Ifewara and Erinmo, respectively. The results of the present study clearly explain the Akoko goiter endemia in the light of modification (s) of thyroid metablism.

Three edible wild mushrooms from Nigeria: their proximate and mineral composition.

The pilei (caps) and the stipes (stalks) of the button and early open-cap (cup) stages of Lentinus subnudus, Psathyrella atroumbonata and Termitomyces striatus were assayed separately for their proximate and mineral composition. The differences observed in the contents of some of the proximate components seem to be related to species and mushroom parts. P. atroumbonata was richest in crude and true protein, L. subnudus was richer in crude fiber, ash and carbohydrates. Mineral contents appeared to be dependent on type and parts of the mushrooms analysed. The three mushrooms were good sources of magnesium, zinc and iron. L. subnudus contained between 14.83 and 20.00 ppm of iron, P. atroumbonata contained between 20.01 and 22.09 ppm and T. striatus contained between 17.13 and 22.93 ppm of iron. The pilei of P. atroumbonata and T. striatus are very good sources of zinc. Zinc contents for the pilei of P. atroumbonata were 63.81 and 64.94 ppm respectively. Zinc contents for T. striatus were 90.45 and 92.49 ppm respectively.

Evaluation of amaranth grains for ogi manufacture.

Grain amaranth was evaluated for its ogi making quality. Amaranth, which produced lower (70%) yield of ogi than corn (80%), had higher protein content of 12.2% for its ogi than that of corn with a corresponding value of 6.7%. Nutrient losses were lower for amaranth than corn ogi. Amylograph pasting viscosity showed that amaranth ogi had slightly higher peak viscosity and lower setback value than corn ogi. It was apparent that amaranth grains would be suitable for ogi manufacture.

Bioavailability to rats of iron from fortified grain amaranth.

In this study, fortified and unfortified grain amaranth seed flour diets and a FeSO4-fortified casein diet (used as a control) were evaluated for their iron (Fe) bioavailability. NaFeEDTA, ferrous fumarate, and FeSO4-fortified grain amaranth were fed to growing Sprague-Dawley weaning male rats. Iron intake, hemoglobin iron (HbFe) gain, Fe availability, total iron binding capacity (TIBC), serum iron, non-haem liver iron and red bloodcell volume (RBV) were determined, and the values were compared with those of the FeSO4-fortified casein diet control. Ferrous fumarate fortified diets gave consistently high values for all these parameters, compared with consistently low values for the amaranth diet without iron fortification. Relative biological values (RBVs) were 0.40, 1.55, 1.75, 1.67 and 1.00 for animals fed on an unfortified amaranth diet, and diets fortified with NaFeEDTA, ferrous fumarate, FeSO4 and casein fortified with FeSO4, respectively. Using FeSO4-fortified casein as control, ferrous fumarate gave a superior RBVs (1.75 vs. 1.00). The RBVs, of the unfortified cereal diets were 40% that of the control, perhaps suggesting low iron absorption from the amaranth cereal. Based on the results of this study, amaranth cereal can be considered an idea food vehicle for iron fortification. The iron fortification of choice is ferrous fumarate.

Studies on some edible wild mushrooms from Nigeria: 1. Nutritional, teratogenic and toxic considerations.

The biological value of 5 mushrooms Chlorophyllum molybditis, Psathyrella atroumbonata, Termitomyces robustus, Termitomyces striatus and Volvariella esculenta from our collection of wild edible mushrooms were determined using weanling rats. C. molybditis supported rapid growth with PER (2.63) higher than the casein control (2.50). P. atroumbonata was average in biological performance (PER 1.50) while T. robustus and V. esculenta did not support growth at all. Rats on T. striatus dried at 60 degrees C for 48 h lost weight rapidly and showed pathological signs of toxicity by the second day. All rats on this diet died by the fourth day of the experiment. When the diet of T. striatus dried at 90 degrees C for about 8 h was fed, the rats gained weight marginally but all survived. Prolonged storage of T. striatus at 60 degrees C for 5-8 weeks also seemed to detoxify the poisonous component such that PER and NPR values were 0.8 and 2.0 respectively. 2 pairs each of adult rats fed C. molybditis and Tricholoma lobayensis diets for 10 days were mated. Rats of C. molybditis diet gave 5 and 6 litters each and only one of these litters seemed to have retarded growth. Rats on T. lobayensis diet did not produce any litters for 14 weeks but the female produced off-spring when mated with control male rats.

Studies on weaning diets in Nigeria: 2 protein sources.

Protein isolates were extracted from melon, groundnut, and soybean cakes in an aqueous system that could potentially yield both oil and protein from oilseeds quantitatively. Protein isolates obtained were 91.2, 78.6 and 79.5% of the total protein content of melon, groundnut and soybean cakes respectively. Both cakes and isolates were assessed in a rat bioassay while breadfruit, cassava, and corn starch were also investigated as sources of carbohydrate. Results showed that there were no significant differences between feed intake, weight gain and PER of rats fed the cake and the protein isolates except in soybean. Weight gain, PER and NPR were highest in cassava-soybean protein isolate diet followed by cassavacasein diet (control) while performance was only moderate with melon- and groundnut-cassava diets. With melon protein isolate, cassava and breadfruit were better carbohydrate sources than corn starch. In simulated weaning diets, cassava-sucrose-melon-soybean protein isolate based diet performed better (weight gain 33.4 g, PER 1.63, NPR 2.23) than a commercial weaning food (weight gain 30.6 g PER 1.57, NPR 2.18) while replacement of sucrose and cassava at 30% by breadfruit yielded a cost effective diet with good performance (weight gain 29.4 g, PER 1.51, NPR 2.12). Diets where soybean protein served as the sole source of protein or breadfruit, white and yellow maize 'ogi' served as the main source of carbohydrate performed only moderately.

Total substitution of leaf protein in the ration of laying hens.

Laying birds of the Harco strain (crossbred sex-linked Brown Leghorn and Rhode Island Red) were fed rations in which leaf protein replaced 0, 25, 50, 75, and 100% of the soybean meal. These five rations were compared with a standard layer ration that contained fish meal and ground nut cake. The results show that 75% of the soybean meal in layer rations can be replaced by leaf protein without any significant effect in egg production and feed efficiency when compared with the performance of birds receiving fish meal in their diet. Use of leaf protein as the sole supplemental source of protein for the birds significantly (P less than .05) reduced feed intake and also resulted in production of very watery droppings by the birds. Feeding of leaf protein also significantly (P less than .01) increased yolk color score.

On the metabolism of amygdalin. 1. The LD50 and biochemical changes in rats.

The mean lethal dose (LD50) of amygdalin in rats was found to be 880 mg/kg body weight (BW) by oral administration. However, when 600 mg/kg BW was administered orally with beta-glucosidase, all the rats died. Total and Mg ATPase activities of the heart decreased with increasing levels of administered amygdalin. When 200 mg/kg BW amygdalin was administered 2.3 mg (11.7% of the dose) was excreted intact over 48 h. Amygdalin, 7.4 mg (18.5% of the dose) was excreted when the dose was 400 mg/kg BW, while 7.5 mg (12.4% of the dose) was excreted as intact amygdalin when the dosage was increased to 600 mg/kg BW. Thiocyanate excreted within the same 48-h period was 7.0, 9.1, and 9.5 mumol representing 18, 11.2, and 7.8% of the 200, 400, and 600 mg/kg BW oral dosage, respectively. With 300 mg/kg BW amygdalin administered intraperitoneally, 4.1 mg amygdalin and 3.9 mumol thiocyanate representing 13.7 and 6.5% of the dose, respectively, was excreted. Excretion of intact amygdalin and thiocyanate was uniform when the dose was low (200 mg), but with higher doses over 70% of the excreted products were detected in the urine during the first 24 h.

A preliminary survey of aerobic bacteria in breast milk of mothers from the low-income group in Nigeria.

The aerobic bacteria colonizing breast milk of the low-income group in Nigeria were quantified to assess its suitability for use in milk banks. In parallel, the nutritional and health status of donating mothers and their infants were assessed by physicians. The aerobic bacteria contained in the specimens included Streptococcus salivarius, Bacillus cereus, Klebsiella pneumoniae, Enterobacter aerogenes, Streptococcus pneumoniae, Streptococcus pyogenes, Pseudomonas aeruginosa and Staphylococcus epidermides. In general, the microbial load found in these milk samples is lower than levels considered dangerous. An analysis of the results showed that 50% of the mother's milk is contaminated, 17% of which was infected with primary pathogens. There was no correlation between demographic data, nutritional or health status of either mother or infant and microbial load in mother's milk. Milk obtained from this socio-economic group, is therefore, considered safe for use in milk banks.

On the metabolism of amygdalin. 2. The distribution of beta-glucosidase activity and orally administered amygdalin in rats.

The organs of 15-day-old rats had the highest capability to hydrolyze amygdalin and prunasin, and most of this activity is concentrated in the tissues of the small and large intestines. The activity decreased with age. In adult rats, the ability of the organs to hydrolyze prunasin is higher than that of amygdalin and is concentrated in the spleen, large intestine, and kidney (35.0, 15.0, and 8.9 micrograms prunasin hydrolyzed . h-1 . g tissue-1). Minced tissues of the liver, spleen, kidney, and stomach contain more hydrolytic capability than the homogenate of these organs, while the reverse is the case with the small and large intestines. When 30 mg amygdalin was orally administered to adult rats, its distribution after the 1st h was as follows: stomach (0.89 mg), small intestine (0.78 mg), spleen (0.36 mg), large intestine (0.30 mg), kidney (0.19 mg), liver (0.10 mg), and serum (5.6 micrograms/mL). At the end of the 2nd h, the highest amygdalin content was found in the large intestine (0.79 mg).

Effect of thiamin status on the metabolism of linamarin in rats.

The effect of graded levels of thiamin on the metabolism of linamarin was investigated in rats. It was observed that on a diet deficient in thiamin, a large amount of linamarin was recovered unchanged in the urine, together with significantly more thiocyanate (SCN-) relative to the control. The least amount of thiocyanate (p less than 0.05 relative to control) was found in animals receiving the highest amount (twice daily requirement) of thiamin in the diet; but the amount of unmetabolized linamarin was similar to the control. It is suggested that thiamin deficiency may be implicated in the aetiology of tropical ataxic neuropathy (TAN) through the thiocyanate overload in people eating large amounts of cassava and cassava derivatives which contain linamarin.

Hydrolysis of linamarin by intestinal bacteria.

Linamarin, a cyanogenic glucoside, was hydrolyzed by Escherichia coli and Streptococcus faecalis but not by Clostridium perfringens when these organisms were grown on a glucose or lactose medium.

Effects of cyanogenic agents on reproduction and neonatal development in rats.

A diet consisting of 50% gari (a form of cassava meal) was found to cause no significant biochemical and haematological changes in adult female rats. Although this diet caused a significant increase in their serum thiocyanate levels, there was no corresponding significant increase in the weight of their thyroid glands. The offspring of these rats had significantly lower birth weights and brain weights and never attained the same adult weights as those of the controls. Adult female rats fed a diet consisting entirely of raw cassava had significantly reduced haematological and biochemical indices. This diet also caused an increased incidence of cannibalism and a significant reduction in the frequency of pregnancy, the average number of the litter and the birth weights among these rats. In addition there was an increased incidence of neonatal deaths among the offspring which also had poor development, reduced brain weights and an increased tendency towards biting their litter-mates. Adult female rats fed diets containing 5 and 10 g cyanide/100 g laboratory diet survived for more than 3 months but never became pregnant. They developed enlarged thyroid glands and tumours of the large intestine. The relevance of these findings to the areas of the world where cyanogenic glycosides form the staple diet is discussed.