Showing papers by "University of Nigeria, Nsukka published in 1968"

Flexural Vibration of Symmetrical Multi-Layer Beams with Viscoelastic Damping:

Abstract: The flexural vibrations of beams can be reduced by introducing sandwiched layers of energy-dissipating materials The equations of motion are derived for flexural vibrations of symmetrical, multi-layer sandwich beams Two types of beams are considered, depending on whether the central layer is energy dissipating when the number of layers will be n = 4i − 1, where i = 1, 2,…, or whether the material of the central layer is perfectly elastic when n = 4i + 1 The total number of equations of motion will be i + 1 for each type These equations will be non-linear when the properties of the energy-dissipating materials are strain dependent A numerical method of solution has been introduced by transforming the equations of motion into sets of non-dimensional simultaneous equations and using finite difference methods The simplest type of beam has three layers but even this leads to a set of four simultaneous equations of the twelfth orderIt is shown as an example that the strain dependence of a typical viscoel

Studies on the movement, the cytology and the associated micro‐organisms of the intestine of Aspiculuris tetraptera (Nematoda)

Abstract: The intestine of the parasitic nematode Aspiculuris tetraptera has been shown to undergo periodic contractions which suggested that muscles were associated with the intestine. Examination of sections of the intestine has shown that the intestinal cells are similar to those of other nematodes which have been described at the ultra-structural level but there is a network of muscle fibres around the whole of the intestine. There are many virus-like particles in the epithelial cells; yeast-like micro-organisms in the lumen of the intestine are attached to the apical surface of the epithelial cells and they replace some of the microvilli. The part played by the muscle network during digestion and defecation is discussed.

Comparative studies of upland and swamp rice varieties ( Oryza sativa L. ). I. Effect of soil moisture on growth and nutrient uptake

Abstract: Growth and nutrient uptake by an upland rice variety, Agbede and a swamp rice variety, BG 79, were studied under four different soil moisture regimes (60, 80, 100% soil moisture saturation and flooding). BG 79 (Swamp rice) ultimately attained greater mean total dry weight than Agbede (Upland rice), except in the flooding treatment, where the reverse applied. For both, 100% soil moisture saturation gave the greatest total dry weight increase, whereas the driest soil depressed dry-matter production: plants grown on soil maintained at 80% moisture saturation ultimately attained greater mean total dry weight than those grown on flooded soil. Flooded plants of the swamp rice outyielded plants grown on soil maintained at 80% moisture saturation, but the reverse applied to the upland rice. Total leaf numbers were usually greater in BG 79 than in Agbede during the tillering and mid-vegetative stages. Increase in the soil moisture up to complete saturation increased the total leaf number in both varieties. Mean leaf area was greater in Agbede than in BG 79 during the tillering and midvegetative stages. During these two periods of growth the 100% saturation treatment produced plants with the greatest leaf area, whereas 60% soil moisture saturation produced plants with the smallest leaf area in both varieties. BG 79 had more shoots than Agbede. During tillering saturated and flooded soil encouraged the production of shoots in both varieties, but the driest soil prolonged the tillering period, especially in BG 79. Final shoot number tended to decrease with decreasing soil moisture. The percentage shoot mortality in Agbede was not significantly affected by soil moisture regimes, but BG 79 plants grown on the driest and saturated soil had significantly greater percentages of shoot mortality than flooded plants. In both varieties, plants grown on the driest soil had significantly greater percentage shoot mortality than those grown on soil maintained at 80% moisture saturation. Mean Relative Leaf Growth Rate and Net Assimilation Rate were significantly faster in BG 79 than in Agbede variety, but the reverse applied with regard to Leaf Weight Ratio. In both varieties flooded plants had the lowest concentration of manganese, especially during tillering. The small adsorption of Mn with flooding is attributed to a probable antagonism between iron and manganese.

Comparative studies of upland and swamp rice varieties ( Oryza sativa L.) II. Effect of varying supply of manganese on growth and yield

Abstract: Upland rice (Agbede) and swamp rice (BG 79) varieties grown on flooded soil, and on soil maintained at 80 and 100% moisture saturation were sprayed with solutions containing 0 ppm (MO), 10 ppm (Ml), and 20 ppm (M2) of manganese. The M 2 treatment depressed total dry weight and dry weights of leaf laminae, stems, leaf sheaths and root of both varieties grown on soil maintained at either 80 or 100% moisture saturation. The M 1 treatment increased the ear weight of Agbede grown on soil maintained at either 80 or 100% moisture saturation, while the M 2 treatment increased the ear weight of plant grown on saturated soil. In flooded soil both the M 1 and M 2 treatments significantly increased dry weight of Agbede plants, but only the M 2 treatment increased ear dry weight of BG 79. The ear weight of Agbede plants receiving M 0 and M 1 treatment decreased with increasing soil moisture while that of BG 79 increased. It is considered that manganese supply limits yield of Agbede grain grown on flooded soil.