Quality of Tigris River passing through Baghdad for irrigation

The effect of Baghdad city on the water quality of the Tigris River was studied from April 1977 to March 1978. The chemical and physical characteristics of the water which are necessary in judging the quality of water for irrigation were studied. It was found that Baghdad was responsible for increasing the water salinity from 390 to 443 mg l^?1. Total hardness and turbidity were increased when the river passed through Baghdad. The increase in the total hardness was mostly due to the increase in Mg concentration. The results also suggested that there should be no problem from the heavy metals or inorganic N in this water when used for irrigation. The Tigris River water in Baghdad was classified as classC ₂ S ₁; that is water of second class with regard to salinity and first class with regard to sodicity.     

Root and shoot competition between established grass species and newly sown seedlings during spring growth

Competition between established Dactylis glomerata or Festuca pratensis / Taraxacum officinale swards and seedlings of Trifolium pratense was studied under field conditions in Norway. Root competition from the Festuca pratensis / Taraxacum officinale sward was significantly greater than that from a Dactylis glomerata sward. The balance in root and shoot competition varied between experimental years because of variation in environmental conditions. In the first experimental year, root competition had a greater effect on seedling dry weight than shoot competition, whereas the opposite was found in the second year. However, both root and shoot competition (full competition) in comparison with no competition gave proportionally the same effects in both years, indicating that an alleviation in root competition will be followed by intensified shoot competition. An increasing effect of shoot competition with time on plant dry weight was found. In a second experiment, seedlings of Lolium perenne and Trifolium pratense produced the highest plant dry weights in competition with an established Phleum pratense sward, followed by seedlings of Poa pratensis , Phleum pratense and Trifolium repens in decreasing order. However, no interactions between seedling species and competition treatments were found, indicating no differences in sensitivity between seedling species to competition from the established grass sward. The results are discussed in the context of renovating grassland by direct drilling.     

Bioadhesive Controlled Metronidazole Release Matrix Based on Chitosan and Xanthan Gum

Metronidazole, a common antibacterial drug, was incorporated into a hydrophilic polymer matrix composed of chitosan xanthan gum mixture. Hydrogel formation of this binary chitosan-xanthan gum combination was tested for its ability to control the release of metronidazole as a drug model. This preparation (MZ-CR) was characterized by in vitro, ex vivo bioadhesion and in vivo bioavailability study. For comparison purposes a commercial extended release formulation of metronidazole (CMZ) was used as a reference. The in vitro drug-release profiles of metronidazole preparation and CMZ were similar in 0.1 M HCl and phosphate buffer pH 6.8. Moreover, metronidazole preparation and CMZ showed a similar detachment force to sheep stomach mucosa, while the bioadhesion of the metronidazole preparation was higher three times than CMZ to sheep duodenum. The results of in vivo study indicated that the absorption of metronidazole from the preparation was faster than that of CMZ. Also, MZ-CR leads to higher metronidazole C_max and AUC relative to that of the CMZ. This increase in bioavailability might be explained by the bioadhesion of the preparation at the upper part of the small intestine that could result in an increase in the overall intestinal transit time. As a conclusion, formulating chitosan-xanthan gum mixture as a hydrophilic polymer matrix resulted in a superior pharmacokinetic parameters translated by better rate and extent of absorption of metronidazole.     

Development of hatchery technology for the silver pomfret Pampus argenteus (Euphrasen): effect of microalgal species on larval survival

The silver pomfret Pampus argenteus (Euphrasen) is a new candidate for aquaculture and there is not much information available on its larval rearing. Investigations carried out using microalgae alone in the culture system for the initial feeding of the silver pomfret larvae showed that Chlorella, Isochrysis and Nannochloropsis without rotifers are not conducive to the survival of newly hatched larvae. At 6 days after hatching (DAH), a maximum survival of 3% (1.8 ± 1.69%) was observed with Isochrysis followed by Nannochloropsis (0.35 ± 0.21%) and Chlorella (0.25 ± 0.21%). All control larvae died at 6 DAH without microalgae. Further investigations using the above microalgae with rotifers and a mixture of these same microalgae with rotifers showed that significantly higher (P < 0.05) survival could be achieved in the mixture of microalgae with rotifers in the culture system. At 12 DAH, the larval survival was 9.73 ± 1.39% in mixed species of algae compared with that of Isochrysis (6.93 ± 1.86%), Nannochloropsis (6.83 ± 0.61%), Chlorella (5.93 ± 2.76%) and seawater without microalgae or the control (0.73 ± 0.31%). The first incidence of feeding on rotifers at 4 DAH was significantly higher (P < 0.05) in all treatments with microalgae than that of the control. The incidence of feeding in mixed species of algae at 4 DAH (60.0 ± 0.00%) and in Isochrysis (55.0 ± 35.36%) was significantly higher (P < 0.05) than that of Chlorella (40.0 ± 0.00%) and the control (25.0 ± 7.07%). Prey consumption of individual larvae increased significantly (P < 0.01) at 8 DAH compared with that at 4 DAH. During this period, predation on rotifers by larvae was significantly higher (P < 0.05) in mixed species of algae (12.85 ± 5.73 rotifers larva^?1) than that of the control (6.75 ± 1.20 rotifers larva^?1). The fatty acid composition of rotifers used during this investigation shows that significantly higher (P < 0.05) ω3 HUFA was present in rotifers treated with mixed algae plus commercial enrichment media ‘Super Selco’ and ‘DHA Protein Selco’. Rearing of silver pomfret larvae up to the juvenile stage using mixed species of microalgae in the hatchery has been discussed. During 38 days of the larval rearing period, it was possible to achieve 3.6–4.2% larval survival with a mean of 3.9 ± 0.42%, which was considerably higher than in previous attempts (survival up to 1.5%).     

Production and Nutritional Quality of Two Small-Sized Strains of the Rotifer Brachionus plicatilis1

The rotifer Brachionus glicatilis, strain-S (from Japan) and strain-S1 (Pozuelo 1975) were mass cultured using Chlorella and bakers' yeast. Under the same feed regime, a significant increase (P < 0.001) in rotifer strain-S production (44.19 ± 8.50 individuals/mL/d) was observed compared with strain-S1 (29.64 ± 9.38 individuals/mL/d). The population growth rate was significantly higher (P> 0.001), and doubling time was significantly lower (P> 0.0001) in rotifer strain-S than in strain-S1. There was a significant decline (P> 0.001) in birth rate of strain-S rotifers in the culture system compared with strain-S1, suggesting short longevity and deterioration of the culture system while using strain-S. In general, no significant difference (P< 0.05) in the presence of ω3 polyunsaturated fatty acids (ω3 PUFA) in different strains of rotifers was observed.     

Influence of Molecular Weight and Degree of Deacetylation of Low Molecular Weight Chitosan on the Bioactivity of Oral Insulin Preparations

The objective of the present study was to prepare and characterize low molecular weight chitosan (LMWC) with different molecular weight and degrees of deacetylation (DDA) and to optimize their use in oral insulin nano delivery systems. Water in oil nanosized systems containing LMWC-insulin polyelectrolyte complexes were constructed and their ability to reduce blood glucose was assessed in vivo on diabetic rats. Upon acid depolymerization and testing by viscosity method, three molecular weights of LMWC namely, 1.3, 13 and 18 kDa were obtained. As for the DDA, three LMWCs of 55%, 80% and 100% DDA were prepared and characterized by spectroscopic methods for each molecular weight. The obtained LMWCs showed different morphological and in silico patterns. Following complexation of LMWCs with insulin, different aggregation sizes were obtained. Moreover, the in vivo tested formulations showed different activities of blood glucose reduction. The highest glucose reduction was achieved with 1.3 kDa LMWC of 55% DDA. The current study emphasizes the importance of optimizing the molecular weight along with the DDA of the incorporated LMWC in oral insulin delivery preparations in order to ensure the highest performance of such delivery systems.     

Estimation of saturated hydraulic conductivity from double‐ring infiltrometer measurements

This research aims to determine soil vertical saturated hydraulic conductivity (K_s) in situ from the measured steady infiltration rate (I), initial soil properties and double‐ring infiltrometer (DRI) test data. Characterizing the effects of these variables on the measured steady infiltration rate will enable more accurate prediction of K_s. We measured the effects of the ring diameter, head of ponding, ring depth, initial effective saturation and soil macroscopic capillary length on measured steady infiltration rates. We did this by simulating 864 DRI tests with the finite element program HYDRUS‐2D and by conducting 39 full‐scale in situ DRI tests, 30 Mini‐Disk infiltrometer experiments and four Guelph Permeameter tests. The M5′ model trees and genetic programming (GP) methods were applied to the data to establish formulae to predict the K_s of sandy to sandy‐clay soils. The nine field DRI tests were used to verify the computer models. We determined the accuracy of the methods with 30% of the simulated DRI data to compare I/K_S values of the finite element models with estimates from the suggested formulae. We also used the suggested formulae to predict the K_s values of 30 field DRI experiments and compared them with values measured by Guelph Permeameter tests. Compared with the GP method, the M5′ model was better at predicting K_S, with a correlation coefficient of 0.862 and root mean square error (RMSE) of 0.282 cm s^?1. In addition, the latter method estimated K_svalues of the field experiments more accurately, with an RMSE of 0.00346 cm s^?1.     

Studies on the effect of using the rotifer, Brachionus plicatilis, treated with different nutritional enrichment media and antibiotics on the growth and survival of blue-fin sea bream, Sparidentex hasta (Valenciennes), larvae

Studies were carried out to determine the effect of using the rotifer, Brachionus plicatilis (Muller) (S‐type), subjected to different treatments on the growth and survival of blue‐fin sea bream, Sparidentex hasta (Valenciennes), larvae. This was to illustrate the role of mixed algae added to the oil enrichments for the treatment of the rotifers to improve the sea bream larval survival. The highest sea bream larval survival (P < 0.05) was obtained while feeding the larvae with rotifers enriched in a mixture of algae plus half the recommended dose of Super Selco and DHA Protein Selco. No significant difference (P > 0.05) in the larval growth was observed between different treatments. However, larval survival was significantly high (P < 0.05) when rotifers were not treated with antibiotics. The results show that there is no need to use antibiotics to treat the rotifers before feeding the blue‐fin sea bream larvae, providing that the rinsing procedure for rotifers used in this study is followed.