Mechanical degradation hampers the practical usage of polymers for turbulent drag reduction
application. Mechanical degradation refers to the chemical process in which the activation energy of
polymer chain scission is exceeded by mechanical action on the polymer chain, and bond rupture
occurs. When a water-soluble polymer and surfactant are mixed in water solution, the specific structures
(aggregates) are formed, in which polymer film is formed around micelle. In this work, Xanthan gum (XG) –
Sodium lauryl ether sulfate (SELS) complex formation and its effect on percentage viscosity reduction
(%VR) was studied. It was found that SELS surfactant reduced the mechanical degradation of XG much
more efficiently than this polymer alone. Xanthan Gum (XG) has been tested for its shear stability and
degradability. 0.5% and 1.0 % by weight concentration solutions were exposed to shear stirring at different
speeds and time; also 0.5% through 1.5% by weight concentration solutions of SELS were added to XG
solutions to determine the ability of SELS to reduce the mechanical degradation of XG. It has been noticed
by measuring the percentage viscosity reduction (%VR) of the mixture of XG-SELS that the % VR
decreases when added this surfactant to XG polymer
This study aimed to show the histological changes that 0ccured in Culex pipiens pipiens larvae and adults infected with Beauveria bassiana . The 4th instar larvae and adult mosquitoes were infected with B.bassiana in 10-4 spore/ml dilution, after 96 hours histological section was studied showing that the fungi infected all the body parts specially Cuticle , Epiderms, fat bodies and midgut. After 120 hours of exposure to the fungi the insect have a white appearance and covered with a thick coat of hyphea. Thus study shows biological control of B .bassiana on mosquitoes.
In this study, nano TiO2 was prepared with titanium isopropoxide (TTIP) as a resource to titanium oxide. The catalyst was synthesized using phosphotungstic acid (PTA) and, stearyl trimethyl ammonium bromide (STAB) was used as the structure-directing material. Characterization of the product was done by the X-ray diffraction (XRD), X-ray fluorescent spectroscopy (XRF), nitrogen adsorption/desorption measurements, Atomic Force Microscope (AFM) and Fourier transform infrared (FTIR) spectra, were used to characterize the calcined TiO2 nanoparticles by STAB and PWA. The TiO2 nanomaterials were prepared in three crystalline forms (amorphous, anatase, anatase-rutile). The results showed that the nanoparticles of anatase TiO2 have good cata
... Show MoreThe analysis of survival and reliability considered of topics and methods of vital statistics at the present time because of their importance in the various demographical, medical, industrial and engineering fields. This research focused generate random data for samples from the probability distribution Generalized Gamma: GG, known as: "Inverse Transformation" Method: ITM, which includes the distribution cycle integration function incomplete Gamma integration making it more difficult classical estimation so will be the need to illustration to the method of numerical approximation and then appreciation of the function of survival function. It was estimated survival function by simulation the way "Monte Carlo". The Entropy method used for the
... Show Morene,؛Stability constants were determined for complexes of amino acids : L-leuc tryptophane and Aspartic acid with thorium (IV ) and uranyle ( U02++) ions at ؛ serine
Oscillation criteria are obtained for all solutions of the first-order linear delay differential equations with positive and negative coefficients where we established some sufficient conditions so that every solution of (1.1) oscillate. This paper generalized the results in [11]. Some examples are considered to illustrate our main results.
This paper presents experimental results regarding the behaviours of eight simply supported partially prestressed concrete beams with internally unbonded tendons, focusing particularly on the effect of three different variables: concrete compressive strength,