148 research outputs found
Synthesis, Crystal Structure and Characterization of [(CH3 CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O)
Single crystals of [(CH3CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O) were grown by the slow evaporation technique and characterized by means of single-crystal X-ray diffraction, FT-IR and Raman spectroscopy. The title compound belongs to the triclinic space group P with the following unit cell dimensions: a =7.5425(4) Å, b=9.8464 Å, c=13.7671(6) Å, α=89.951(3)°,β=89.753(3)°, γ=81.861(3)°, Z=4. These structures have solved using direct methods and refined by least-squares analysis. The structure was solved by the direct method and refined to final R value of 0.0567. The projection of [(CH3CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O) in the plan (a,b) shows an arrangement in layers perpendicular to the direction b . The structure consists of infinite parallel two-dimensional planes built connected ions and water molecules by strong O-H…O and O-H…Cl hydrogen bonding
Crystal structure, thermal behavior and vibrational studies of tetraethylammonium dihydrogenarsenate bis-arsenic acid [(C2H5)4N].[H2AsO4].[H3AsO4]2
An organic-inorganic hybrid compound of tetraethylammonium dihydrogenarsenate bis-arsenic acid salts of formula [(CH3CH2)4N].[H2AsO4].[H3AsO4]2(TEAs) were grown by the slow evaporation and characterized by means of single crystal X-ray diffraction, thermal analysis, FT-IR and Raman spectroscopy. This compound crystallize in the space groups Cc with unit cell parameters, a= 20.105(2) Å; b= 7.342(4) Å, c = 15.292(2) Å, γ = 115(4)°, Z = 4, R= 0.07. The structure has solved using direct methods and refined by least-squares analysis. In this case, the structure consists of infinite parallel two-dimensional planes built of mutually H2AsO4−, H3AsO4 tetrahedra connected by strong O-H···O hydrogen bonding. The thermoanalytical properties were studied using TG of TEAs method in the temperature ranges from 300 to 440 K for this hygroscopic sample. DSC measurement was carried out in the temperature range from 305 to 425 K
Electrochemical behavior of Auramine O dye in aqueous solutions at lead dioxide electrode
Electrochemical behavior of Auramine O (AO) was studied by galvanostatic electrolysis at lead dioxide (Ta/PbO2) anodes. The influence of operating parameters, such as current density, initial concentration of AO, temperature and initial pH value was investigated. The oxidation kinetics of the AO was followed by HPLC, UV / visible spectrophotometry and the measurement of chemical oxygen demand (COD). The experimental results showed that the electrochemical process was suitable for almost completely removing COD, due to the production of the hydroxyl radicals at the anode surface. The oxidation of AO is dependent on its initial concentration, current density, temperature and pH. COD decay follows a pseudo first-order kinetic and the process was under mass transport control. The HPLC analysis showed that the main AO oxidation products formed during electrolysis are the hydroquinone (HQ) representing the reduced form of benzoquinone (BQ) and carboxylic acids (CA). The proposed AO anodic oxidation into (BQ) is mainly based on an alternance of indirect monoelectronic discharge by the mediation of hydroxyl radicals and hydrolysis steps. The electrochemical oxidation of AO can be used as an economically adequate way for a pre-treatment of waters containing this dye followed by biological treatment
A Nelder–Mead algorithm-based inverse transient analysis for leak detection and sizing in a single pipe
Abstract
In this paper the results of an experimental validation of a technique for leak detection in polymeric pipes based on the inverse transient analysis (ITA) are presented. In the proposed ITA the Nelder–Mead algorithm is used as a calibration tool. Experimental tests have been carried out in an intact and leaky high-density polyethylene (HDPE) single pipe installed at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy. Transients have been generated by the fast and complete closure of a valve placed at the downstream end section of the pipe. In the first phase of the calibration procedure, the proposed algorithm has been used to estimate both the viscoelastic parameters of a generalized Kelvin–Voigt model and the unsteady-state friction coefficient, by minimizing the difference between the numerical and experimental results. In the second phase of the procedure, the calibrated model allowed the evaluation of leak size and location with an acceptable accuracy. Precisely, in terms of leak location the relative error was smaller than 5%
Crystal structure and spectroscopic study of bis-tetrapropylammonium hexachlorodicuprate(II), [N(C3H7)4]2Cu2Cl6
Single crystals of the bis-tetrapropylammonium hexachlorodicuprate(II), [N(C3H7)4]2Cu2Cl6, were grown by slow evaporation solution technique at room temperature. The compound was characterized by Raman, IR and single crystal X-ray diffraction studies. Crystal data for C12H28Cl3CuN (M = 356.24 g/mol): triclinic, space group P-1 (no. 2), a = 9.3851(2) Å, b = 9.3844(2) Å, c = 11.8837(3) Å, α = 106.3330(11)°, β = 100.0280(12)°, γ = 113.2830(12)°, V = 872.95(3) Å3, Z = 2, T = 293(2) K, μ(MoKα) = 1.693 mm-1, Dcalc = 1.355 g/mm3, 8056 reflections measured (6.64 ≤ 2Θ ≤ 62.02), 5526 unique (Rint = 0.0303) which were used in all calculations. The final R1 was 0.0427 (>2σ(I)) and wR2 was 0.1312 (all data). The atomic arrangement can be described by alternating organic and inorganic layers parallel to the (101) plan, made up of tetrapropylammonium groups and Cu2Cl6 dimers, respectively. In crystal structure, the inorganic layers, built up by Cu2Cl6 dimers, are connected to the organic ones through hydrogen bonding C-H…Cl and Van der Waals interaction in order to build cation-anion-cation cohesion. These interactions cause to the formation of a three-dimensional supramolecular architecture
Cancers du larynx etude retrospective à propos de 90 cas
Objectif : Le cancer du larynx est parmi les premiers cancers de la sphère oto-rhino laryngée. La dysphonie constitue le maître symptôme révélateur et peut être associée à une dyspnée selon la localisation tumorale. Il s’agit essentiellement d’un carcinome épidermoide. L’alcoolo-tabagisme joue un rôle important dans la genèse de ce cancer.Matériel et méthodes: Notre étude est rétrospective à propos de 90 cas colligés sur une période de 18 ans (1990-2007).Résultats : La prédominance du sexe masculin est nette avec une seule femme dans notre série. Le pic d’âge est entre 60 et 70 ans. 98,9% de nos patients sont des fumeurs chroniques. 14,4% ont été suivis pour une laryngite chronique. La dysphonie a été retrouvée chez tous nos patients. Le délai de consultation moyen est relativement long avec une moyennede 8 mois. Le point de départ de la tumeur a été le plan glottique dans 72,2% et sus glottique dans 23,4%. Le type histologique le plus fréquent est le carcinome épidermoïde dans 92,2%. Le bilan d’extension a systématiquement comporté une endoscopie sous anesthésie générale avec une tomodensitométrie. La majorité de nos malades ont été classésT3-T4 et ceci dans 31,4%. Le taux de survie globale à 5 ans a été de 57,1%.Conclusion : Le cancer du larynx est un cancer du sujet de sexe masculin surtout alcoolo-tabagique. Le bilan endoscopique et radiologique essentiellement scanographique va permettre un bilan d’extension et guider ainsi la conduite thérapeutique. Le traitement est essentiellement chirurgical, couplé parfois à une radiothérapie ou une chimiothérapie.Le pronostic est le plus fréquemment favorable surtout si le diagnostic est précoce.Mots-clés : Larynx, Cancer, Tomodensitométrie,Traitemen
THERAPEUTIC MANAGEMENT OF A CASE OF CHRONIC MYOFACIAL PAIN
Myofacial pain is a common form of temporomandibular disorders. It is manifested by a sensory, motor and autonomous symptoms caused by trigger points. These pains can significantly affect patients’ quality of life, when they persist. Several etiological factors have been implicated in the genesis of the myofacial pain: muscle overload, emotional tension, harmful postural habits, fatigue, and hypovitaminosis... The diagnosis of myofacial pain is based on a pertinent history and clinical examination. Several therapeutic options alone or in combination have proven their effectiveness. This article aims, through a clinical case, to focus on myofacial pain, possible therapeutics, by focusing on the contribution of the occlusal appliance in the management of these pains
3,12-Diaza-6,9-diazoÂnia-2,13-dioxotetraÂdecane bisÂ(perchlorate)
The crystal structure of the title diprotonated diacetylÂtriethylÂeneÂtetraÂmine (DAT) perchorate salt, C10H24N4O2
2+·2ClO4
−, can be described as a three-dimensional assembly of alternating layers consisting of diprotonated diacetylÂtriethylÂeneÂtetraÂmine (H2DAT)2+ strands along [100] and the anionic species ClO4
−. The (H2DAT)2+ cations in the strands are connected via N—H⋯O hydrogen bonding between the acetyl groups and the amine groups of neighbouring (H2DAT)2+ cations. Layers of (H2DAT)2+ strands and perchlorate anions are connected by a network of hydrogen bonds between the NH and NH2 groups and the O atoms of the perchlorate anion. The asymmetric unit consits of one perchlorate anion in a general position, as well as of one cation that is located on a center of inversion
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