Primary production and respiration of the phytoplankton in the Blue and White Niles at Khartoum

Phytoplankton production and respiration in the Blue Nile and White Nile at Khartoum were measured during the period November 1969–January 1971 using the light and dark bottle technique. Maximum rates of production coincided with periods of maximum phytoplankton densities. In the Blue Nile gross production varied between 0.00 gCm^–3d^–1 during the flood season and 2.19 gCm^–3d^–1 (0.49 mgO₂l^–1h^–1) during November 1969. In the White Nile the range was from 0.41 gCm^–3d^–1 (0.09 MgO₂l^–1h^–1) in May to 3.74 gCm^–3d^–1 (0.83 MgO₂l^–1h^–1) in November. The maximum rates of respiration in the Blue Nile and White Nile were 0.10 and 0.63 MgO₂l^–1h^–1 respectively. The ratios net:gross production were generally higher in the White Nile than in the Blue Nile.     

Eflect of Relative Humidity on the Bactericidal Activity of Propylene Oxide Vapor

Because of the low toxicity of its breakdown product, propylene oxide (PO) vapor will play an increasingly important role in the preservation of foods. It is therefore necessary that the diversified variables which influence effectiveness of PO treatment be thoroughly investigated and understood prior to advocating its general use in industry. Accordingly, the present study was undertaken to determine the effect of relative humidity (RH) upon the bactericidal activity of PO sterilant atmospheres. Death rates were established at increasing RH values of < 1, 52, 65, 80, and 98% and under constant conditions of concentration, pressure, and temperature. Test bacterial populations were preconditioned to corresponding moisture levels. Results indicate that gram-positive cocci were relatively insensitive to PO vapor at dry conditions but became progressively less resistant with the increase in RH up to a maximum of 65 to 70%. Lactic acid bacteria and gram-negative rods were much more sensitive at dry conditions, showing much less dependency upon water vapor. Bacillus subtilis spores elicited the highest degree of resistance but the death rate substantially increased with the increase in RH.     

Observations on the venous system of three species of Polypterus (Pisces)

The venous system of Polypterus exhibits general asymmetry. The features that characterize the venous system of this peculiarly African fish are the possession of many blood sinuses, the segmental drainage of blood, the continuation of the posterior cardinal veins as separated vessels and the occurrence of several anastomozes between the latter.
In the absence of any recent comprehensive work on the blood system of this fish, it was thought that investigation of the circulatory system of Polypterus would be valuable. In this paper attention is drawn to Budgettapos;s (1902) original work on a larva of Polypterus senegalus. Contrary to Budgettapos;s findings it is concluded that what he called the "interrenal" vein is in fact the right posterior cardinal vein. It is also found that paired posterior cardinal veins exist in all adults.     

Chemical Composition and Insecticidal Activity against Tribolium Castaneum of Thapsia garganica L. Seed Essential Oil

Due to the several side effects of synthetic pesticides, including environmental pollution, threats to human health, and the development of pest resistance to insecticides, the use of alternative healthy, available and efficient agents in pest management strategies is necessary. Recently, the use of essential oil obtained from aromatic plants has shown significant potential for insect pest management. For this reason, the essential oil isolated from seeds of Thapsia garganica L. was investigated for the first time for its chemical profile, and its toxicity and repellency effects against Tribolium castaneum adults. Qualitative and quantitative analyses of the chemical composition by gas chromatography coupled to mass spectrometry (GC/MS) revealed the presence of 18 organic volatiles representing 96.8 % of the total constituents. The main compounds were 1,4-dimethylazulene (51.3 %) followed by methyl palmitate (8.2 %), methyl linoleate (6.2 %) and costol (5.1 %). Concerning the repellent effect, results revealed that SEO (Seed Essential Oil) was very repellent towards T. castaneum adults, with 100 % repellency after 2 h of exposure. Furthermore, the essential oil exhibited remarkable contact toxicity against T. castaneum (93.3 % of mortality) at the concentration of 10 % (v/v). The median lethal dose (LD₅₀) of the topical application of the seed essential oil was 4.4 %. These encouraging outcomes suggested that the essential oil from T. garganica seeds could be considered a potent natural alternative to residual persistent and toxic insecticides.     

Effects of salt stress on nitrogenase activity and growth of four legumes

The effects of salt stress on nitrogenase (N2-ase) activity, growth and nitrogen content ofVicia faba (L.),Medicago sativa (L.) Merrill,Glycine max andVigna sinensis (L.) were investigated. Four levels of salinity were applied and salt treatments were imposed on inoculated and N-fertilized plants.M. sativa tolerated mild levels of salinity but higher salt concentrations depressed N₂-ase activity of this species. The other three legumes were considerably affected by salt treatments, and N₂-ase activity was significantly reduced by salinity. Vicia faba, carrying elongate nodules, could restore a partial N₂-ase activity upon recovery from salt stress whereasG. max andV. sinesis, both with spherical nodules, could not regain significant activity when salinity was removed. Salt stress retarded growth of both inoculated and N-fertilized plants. The nitrogen content of both treatments was also affected by salinity and the effect was more severe for inoculated than N-fertilized plants.     

A colorimetric method for the determination of indole, and its application to assay of tryptophanase.

Indole reacts with sodium nitrite and glycine-HCl buffer, pH 2.6, to form a red color that is stable for more than 1 week. The reaction is reproducible and is linear over a wide range of indole concentrations (0.05–1.00 μmol). Twelve indole derivatives, including tryptophan, and 17 protein amine acids do not interfere. Indole-3-acetic acid, indole-3-acrylic acid, indole-3-pyruvic acid, 5-indole carboxylic acid, and 5-hydroxyindole-3-acetic acid interfere to varying extents (16–27%). Free indole was determined in biological material containing tryptophan by the present method. The method is also applicable to the assay of tryptophanase activity without prior indole extraction.     

Fast-HBR: Fast hash based duplicate read remover

The Next-Generation Sequencing (NGS) platforms produce massive amounts of data to analyze various features in environmental samples. These data contain multiple duplicate reads which impact the analyzing process efficiency and accuracy. We describe Fast-HBR, a fast and memory-efficient duplicate reads removing tool without a reference genome using de-novo principles. It uses hash tables to represent reads in integer value to minimize memory usage for faster manipulation. Fast-HBR is faster and has less memory footprint when compared with the state of the art De-novo duplicate removing tools. Fast-HBR implemented in Python 3 is available at https://github.com/Sami-Altayyar/Fast-HBR.     

Conceptual Method of Temperature Sensation in Bionic Hand by Extraordinary Perceptual Phenomenon

Lack of temperature sensation of myoelectric prosthetic hand limits the daily activities of amputees.To this end,a non-invasive temperature sensation method is proposed to train amputees to sense temperature with psychophysical sensory substitution.In this study,22 healthy participants took part besides 5 amputee participants.The duration time of the study was 31 days with five test steps according to the Leitner technique.An adjustable temperature mug and a Peltier were used to change the temperature of the water/phantom digits to induce temperature to participants.Also,to isolate the surround-ings and show colors,a Virtual Reality(VR)glass was employed.The statistical results conducted are based on the response of participants with questionnaire method.Using Chi-square tests,it is concluded that participants answer the experiment significantly correctly using the Leitner technique(P value＜0.05).Also,by applying the"Repeated Measures ANOVA",it is noticed that the time of numbness felt by participants had significant(P value＜0.001)difference.Participants could remember lowest and highest temperatures significantly better than other temperatures(P value＜0.001);furthermore,the well-trained amputee participant practically using the prosthesis with 72.58％could identify object's temperature with only once time experimenting the color temperature.