449 research outputs found

    Norm inequalities for vector functions

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    We study vector functions of Rn{\mathbb R}^n into itself, which are of the form xg(x)x,x \mapsto g(|x|)x\,, where g:(0,)(0,)g : (0,\infty) \to (0,\infty) is a continuous function and call these radial functions. In the case when g(t)=tcg(t) = t^c for some cR,c \in {\mathbb R}\,, we find upper bounds for the distance of image points under such a radial function. Some of our results refine recent results of L. Maligranda and S. Dragomir. In particular, we study quasiconformal mappings of this simple type and obtain norm inequalities for such mappings.Comment: 19 page

    Study of the extraction of cobalt(II) from sulphate medium by using capric acid dissolved in chloroform

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    In this work we have first investigated the extraction of cobalt(II) from sulphate medium using capric acid dissolved in chloroform and then the effect of other diluents on the extraction process at 25°C. This study aims to understand the behaviour followed by this metal or, in other words, find its stoichiometry at the end of the extraction. This deportment is strongly dependent on many parameters like pH of the aqueous solution, acid concentration and the nature of the solvent. Each one of these parameters will be discussed. Temperature is another parameter that will be studied in this work. At the end of this research, we have found that stoichiometry of Co(II) complex is of the type CoA2(HR)2 (HR is an abridgment of capric acid). The equilibrium constant Kex and the thermodynamic parameters ΔH°, ΔS°, and ΔG° have been evaluated.Keywords: Capric acid; Cobalt(II); Sulphate medium; Solvent polarity, Temperature effect

    Liquid-liquid extraction of iron (III) from Ouenza iron ore leach liquor by tributylphosphate

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    The solvent extraction of iron (III) from the hydrochloric acid leach liquor of iron ore from mine of Ouenza, Algeria with tributylphosphate (TBP) in chloroform was studied. The effect of several parameters, such as contact time, HCl concentration, TBP concentration and chloride inorganic salt (KCl) concentration on the efficiency of extraction of iron was examined at 19±2°C. It was found that, for 2 min 3M TBP in presence of 5M HCl and 2 M KCl solutions led to a high yiel of extraction (98.57 %) of iron (III).The stoichiometry of the extracted species was determined by using the method of slope analysis. The number of moles of H+, Cl- and TBP associated with the extracted species was determined and the extracted species was found to be HFeCl4 (TBP)2.Keywords: solvent extraction; iron (III); Tributylphosphate; leach liquor; Mine Ouenz

    Neurosurgical management of anterior meningo-encephaloceles about 60 cases

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    Anterior meningo-encephaloceles (AME) are congenital malformations characterized by herniation of brain tissue and meninges through a defect in the cranium, in frontal, orbital, nasal and ethmoidal regions. The management of this complex congenital malformation is controversial according to whether use, an intracranial, extra-cranial or combined approach. This is the first largest series published in Africa, in which we present our experience in the operative management of AME; we share our recommendation in technical consideration for surgical approach with review of the literature. All patients beneficed of neuro-radiological investigations including Plan X rays, Spiral Three dimensional CT scan and MRI. Ophthalmologic and maxillo-facial evaluations were done in all the cases. MEA are surgically approached in various ways, mainly on the basis of its location and type, by cranio-facial approach in one-step, or in two stages by intracranial approach followed by facial approach, only by cranial approach or facial approach. The surgical results were evaluated in the follow up on the basis of disappearance of cranio-facial tumefaction with correction of hypertelorism. 60 children with AME were treated in our department between January 1992 and December 2012. The mean age at time of surgery was 14 months (20 days to 18 years) with slight men predominance (28 females/32 males). Cranio-facial team operated 21 patients, 16 were operated in two stages by intracranial approach followed by facial approach, 20 cases beneficed the neurosurgical approach and three only the facial approach Some post operative complications were observed: 2 cases of post operative hydrocephalus underwent shunt; CSF fistulas in three cases cured by spinal drainage, one death due to per operative hypothermia, 3 cases of recurrence how needed second surgery. After mean follow up for 80 months (1 year to 19 years) theses techniques permitted a good cosmetics results in 42 cases, average cosmetics results in 8 cases, poor results in 5 cases and worse cosmetics results in 4 cases, The AME are rare conditions we used the multiples approach first intracranial approach followed by facial approach, but after 1998 we used one-step correction by combined approach, only cranial approach when needed or facial correction

    Methidathion-induced hematological, biochemical and hepatohistological alterations in rat: Ameliorative effects of selenium and zinc

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    The aim of this study was to determine the effect of a sub-acute 4-week exposure to methidathion (MD) on the hematological system and hepatic integrity of rats. We also assessed whether co-administration of micronutrients such as selenium (Se) and zinc (Zn) prevented MD-induced hepatic damage. Rats were randomly divided into four groups of six each: the first group served as a control which received standard diet, the second group received both Se (0.5mg/kg of diet) and Zn (0.227 g/l drinking water), the third group received only MD (5 mg/kg b.w. by gavage using corn oil as a vehicle), and the fourth group received MD and combined selenium and zinc. After four weeks, exposure to MD induced a significant increase in plasmatic activities of AST, ALT, ALP, LDH, and liver malondialdehyde level. In contrast, reduced glutathione level (GSH), and the activities of catalase (CAT), superoxide dismutase (SOD), and the glutathione peroxidase (GPx) content of hepatic tissue decreased significantly. Moreover, treatment with Se and Zn in MD-treated rats maintained all the biochemical parameters cited above. In conclusion, the obtained results indicate the ability of Se and Zn to attenuate the MD-induced liver and erythrocytes oxidative damage.Key words: Biochemical studies, liver, methidathion, oxidative stress, rat, selenium, zinc

    Wilker and Huygens type inequalities for mixed trigonometric-hyperbolic functions

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    Motivated by the work of J. S\'andor [19], in this paper we establish a new Wilker type and Huygens type inequalities involving the trigonometric and hyperbolic functions. Moreover, in terms of hyperbolic functions, the upper and lower bounds of sin(x)/x and tan(x)/x are given

    On an inequality of Redheffer

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    Solvent extraction of nickel(II) from sulphate solution using capric acid

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    In this work we have studied the extraction of nickel(II) from a sulphate medium with capric acid noted (HA) in chloroform at 25°C in this study we will try to understand the behavior of this metal by varying a set of parameters like pH , the extractant concentration, polarity of solvent, effect of temperature on the extraction of this metal was also discussed. stoïchiometry of extracted species in the organic phase is NiR2(HR)2 , the equilibrium constants have been evaluated as well as thermody
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