1,230 research outputs found

    Ionic Liquids Containing Sulfonium Cations as Electrolytes for Electrochemical Double Layer Capacitors

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    In this work, we report on the behavior of ionic liquids (ILs) containing sulfonium cations as electrolytes for electrochemical double layer capacitors (EDLCs). Physical properties such as viscosity and ionic conductivity are reported over a range of temperatures for ILs containing the diethylmethyl sulfonium [S221], triethyl sulfonium [S222], and diethylpropyl sulfonium [S223] cations paired with the bis(trifluoromethanesulfonyl) imide [Tf2N] anion. The size and structure of the cations are shown to influence the physical and electrochemical properties of the ILs, with a significant degree of ionic coordination being evident in [S223][Tf2N]. The electrochemical behavior of these ILs in EDLCs was compared with that of a fairly established IL electrolyte, N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide ([Pyr14][Tf2N]), and it is shown that [S221][Tf2N] can perform better in terms of energy and power at room temperature, despite operating at a much reduced potential

    Evaluation of three different approximations for the solution of the direct problem on electrical impedance tomography

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    Neste trabalho foram comparadas 3 diferentes soluções para o problema direto da tomografia de impedância elétrica utilizando o método das diferenças finitas. Nesta técnica são posicionados elétrodos no contorno/fronteira de um volume a ser estudado e, em 2 deles, são injetados padrões de correntes e, nos elétrodos restantes, realizadas medidas do potencial elétrico. A inversão numérica dos dados permite a reconstrução do domínio analisado. Duas novas aproximações são propostas para o problema direto e comparações são realizadas a partir de resultados disponíveis na literatura. Com o estudo aqui realizado, para uma das aproximações propostas foi observada uma melhora significativa da acurácia comparada aos resultados obtidos com a aproximação da literatura.The present study compares three different solutions for the direct problem of Electrical Impedance Tomography using the finite difference method. In this technique, electrodes are positioned on the boundary of a volume to be studied, and in two of them current patterns are injected and measurements of electrical potential are made in the remaining electrodes. The numerical inversion of the data allows reconstruction of the analyzed domain. Two new approximations are proposed for the direct problem and comparisons are performed based on results available in the literature. In the study performed here, in one of the proposed approximations it was observed a significant improvement in accuracy compared to results obtained with the approximations in the literature.Peer Reviewe

    Fuzzy set based multiobjective allocation of resources and its applications

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    AbstractThis paper presents results of research into the use of the Bellman-Zadeh approach to decision making in a fuzzy environment for solving multiobjective optimization problems. Its application conforms to the principle of guaranteed result and provides constructive lines in obtaining harmonious solutions on the basis of analyzing associated maxmin problems. The use of the Bellman-Zadeh approach has served as a basis for solving a problem of multiobjective allocation of resources (or their shortages) and developing a corresponding adaptive interactive decision-making system (AIDMS1). Its calculating kernel permits one to solve maxmin problems using an algorithm based on a nonlocal search (modification of the Gelfand's and Tsetlin's “long valley” method). The AIDMS1 includes procedures for considering linguistic variables to reflect conditions that are difficult to formalize as well as procedures for constructing and correcting vectors of importance factors for goals. The use of these procedures permits one to realize an adaptive approach to processing information of a decision maker to provide successive improving of the solution quality. C++ windows of the AIDMS1 are presented for input, output, and special possibilities related to considering linguistic variables and constructing and correcting vectors of importance factors. The results of the paper are universally applicable and are already being used to solve power engineering problems

    The Influence Of Tubule Density And Area Of Solid Dentin On Bond Strength Of Two Adhesive Systems To Dentin

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    Purpose: To determine the correlation between the tubule density (TD) and the area occupied by solid dentin (ASD) with the bond strength of one conventional and one self-etching adhesive system to dentin. Materials and Methods: The crown of extracted human third molars was transversally sectioned with a diamond saw to expose either superficial, middle, or deep dentin. The three groups of dentin surfaces were randomly divided and bonded with either Clearfil Liner Bond 2V (LB) or Prime & Bond 2.1 (PB) adhesive systems according to manufacturer's directions. Resin composite buildup crowns (10.0 mm high) were incrementally constructed on the bonded surfaces and the teeth stored in water at 37°C. After 24 h of storage, the teeth were vertically, serially sectioned in both x and y directions to obtain several bonded sticks of approximately 0.7 mm2 cross-sectional area. Each stick was tested in tension in a EMIC DL-500 tester at 0.5 mm/min until failure. After testing, the dentin side of the fractured specimen was gently abraded with a 1000-grit SiC paper, etched with 37% phosphoric acid for 15 s and allowed to air dry. SEM micrographs at 1000X and 4000X magnification were taken to permit calculation of the TD (number of tubules/mm2) and ASD (% of total area) at the site of fracture. Correlation between TD and ASD with the bond strength data was performed by linear regression. All statistical analysis was done with a = 0.05. Results: Overall bond strength (MPa) for LB was 26.0 ± 10.2, and 42.6 ± 15.2 for PB. There was a significant direct relationship between bond strength and ASD for both materials (r2 = 0.20, p < 0.05 and r2 = 0.66, p < 0.01, respectively for LB and PB). PB bond strength dropped significantly as the TD increased (r2 = 0.63, p < 0.05), while LB was not sensitive to TD (r2 = 0.05, p > 0.05). Mean bond strength of PB was significantly higher than LB for both superficial and middle dentin (p < 0.05), while there was no significant difference for deep dentin (p > 0.05). Conclusion: Regional variations in TD and ASD may modify bond strength of both conventional and self-etching adhesive systems. Bonding sites with larger ASD seem to yield higher bond strengths regardless of the type of adhesive system used.34315324Burrow, M.F., Takakura, H., Nakajima, M., Inai, N., Tagami, J., Takatsu, T., The influence of age and depth of dentin on bonding (1994) Dent Mater, 10, pp. 241-246Carrigan, P.J., Morse, D.R., Furst, M.L., Sinai, I.H., A scanning electron microscopic evaluation of human dentinal tubules according to age and location (1984) J Endod, 10, pp. 359-363Fernandes, C.A.O., (2000) Estudo Comparativo da Resistência Adesiva À Dentina Superficial e Profunda Testada Simultaneamente, Empregando-se Dois Sistemas Adesivos, , Thesis, Bauru School of Dentistry, USP, Bauru, SP, BrazilFosse, G., Saele, P.K., Eide, R., Numerical density and distributional pattern of dentin tubules (1992) Acta Odont Scand, 50, pp. 201-210Garberoglio, R., Brännström, M., Scanning electron microscopic investigation of human dentinal tubules (1976) Archs Oral Biol, 21, pp. 355-362Gwinnett, A.J., Quantitative contribution of resin infiltration/hybridization to dentin bonding (1993) Am J Dent, 6, pp. 7-9McCabe, J.F., Rusby, S., Dentine bonding agents - Characteristic bond strength as a function of dentine depth (1992) J Dent, 20, pp. 225-230Nakajima, M., Sano, H., Burrow, M.F., Tagami, J., Yoshiyama, M., Ebisu, S., Ciucchi, B., Pashley, D.H., Tensile bond strength and SEM evaluation of caries-effected dentin using adhesives (1995) J Dent Res, 74, pp. 1679-1688Nery, S., McCabe, J.F., Wassell, R.W., A comparative study of three dental adhesives (1995) J Dent, 23, pp. 55-61Pashley, D.H., Carvalho, R.M., Dentine permeability and dentine adhesion (1997) J Dent, 25, pp. 335-372Pashley, D.H., Ciucchi, B., Sano, H., Carvalho, R.M., Russell, C.M., Bond strength versus dentine structure: A modelling approach (1995) Archs Oral Biol, 40, pp. 1109-1118Pashley, D.H., Ciucchi, B., Sano, H., Yoshiyama, M., Carvalho, R.M., Adhesion testing of dentin bonding agents. A review (1995) Dent Mater, 11, pp. 117-125Pashley, D.H., Clinical correlations of dentin structure and function (1991) J Prosth Dent, 66, pp. 777-781Pashley, D.H., Dentin: A dynamic substrate - A review (1989) Scanning Microsc, 3, pp. 161-174Pereira, P.N.R., Okuda, M., Sano, H., Yoshikawa, T., Burrow, M.F., Tagami, J., Effect of intrinsic wetness and regional difference on dentin bond strength (1999) Dent Mater, 15, pp. 46-53Prati, C., Pashley, D.H., Dentin wetness, permeability and thickness and bond strength of adhesive systems (1992) Am J Dent, 5, pp. 33-38Suzuki, T., Finger, W.J., Dentin adhesives: Site of dentin vs. Bonding of composite resins (1988) Dent Mater, 4, pp. 379-383Tagami, J., Tao, L., Pashley, D.H., Correlation among dentin depth, permeability, and bond strength of adhesive resins (1990) Dent Mater, 6, pp. 45-50Tao, L., Pashley, D.H., Shear bond strengths to dentin: Effects of surface treatments, depth and position (1988) Dent Mater, 4, pp. 373-378Tay, F.R., Gwinnett, A.J., Wei, S.H.Y., The overwet phenomenon: A scanning electron microscopic study of surface moisture in the acid-conditioned, resin-dentin interface (1996) Am J Dent, 9, pp. 109-114Tay, F.R., Sano, H., Carvalho, R.M., Pashley, E.L., Pashley, D.H., An ultrastructural study of the influence of acidity of self-etching primers and smear layer thickness on bonding to intact dentin (2000) J Adhesive Dent, 2, pp. 83-98Yoshiyama, M., Carvalho, R.M., Sano, H., Horner, J., Brewer, P.D., Pashley, D.H., Interfacial morphology and strength of bonds made to superficial versus deep dentin (1995) Am J Dent, 8, pp. 297-302Yoshiyama, M., Sano, H., Ebisu, S., Tagami, J., Ciucchi, B., Carvalho, R.M., Johnson, M.H., Pashley, D.H., Regional strengths of bonding agents to cervical sclerotic root dentin (1996) J Dent Res, 75, pp. 1404-141

    PI3K/AKT/mTOR pathway activation in actinic cheilitis and lip squamous cell carcinomas

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156448/2/jdv16420_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156448/1/jdv16420.pd

    Percolation on two- and three-dimensional lattices

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    In this work we apply a highly efficient Monte Carlo algorithm recently proposed by Newman and Ziff to treat percolation problems. The site and bond percolation are studied on a number of lattices in two and three dimensions. Quite good results for the wrapping probabilities, correlation length critical exponent and critical concentration are obtained for the square, simple cubic, HCP and hexagonal lattices by using relatively small systems. We also confirm the universal aspect of the wrapping probabilities regarding site and bond dilution.Comment: 15 pages, 6 figures, 3 table

    The spin and charge gaps of the half-filled N-leg Kondo ladders

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    In this work, we study N-leg Kondo ladders at half-filling through the density matrix renormalization group. We found non-zero spin and charge gaps for any finite number of legs and Kondo coupling J>0J>0. We also show evidence of the existence of a quantum critical point in the two dimensional Kondo lattice model, in agreement with previous works. Based on the binding energy of two holes, we did not find evidence of superconductivity in the 2D Kondo lattice model close to half-filling.Comment: 4 pages, 1 table, 3 fig

    Signature for heavy Majorana neutrinos in hadronic collisions

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    The production and decay of new possible heavy Majorana neutrinos are analyzed in hadronic collisions. New bounds on the mixing of these particles with standard neutrinos are estimated according to a fundamental representation suggested by grand unified models. A clear signature for these Majorana neutrinos is given by same-sign dileptons plus a charged weak vector boson in the final state. We discuss the experimental possibilities for the future Large Hadron Collider (LHC) at CERN.Comment: Latex2e(epsfig), 12 pages, 8 figures, to appear Physical Review

    Overcoming adaptive resistance in mucoepidermoid carcinoma through inhibition of the IKK-β/IκBα/NFκB axis

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    Patients with mucoepidermoid carcinoma (MEC) experience low survival rates and high morbidity following treatment, yet the intrinsic resistance of MEC cells to ionizing radiation (IR) and the mechanisms underlying acquired resistance remain unexplored. Herein, we demonstrated that low doses of IR intrinsically activated NFκB in resistant MEC cell lines. Moreover, resistance was significantly enhanced in IR-sensitive cell lines when NFκB pathway was stimulated. Pharmacological inhibition of the IKK-β/IκBα/ NFκB axis, using a single dose of FDA-approved Emetine, led to a striking sensitization of MEC cells to IR and a reduction in cancer stem cells. We achieved a major step towards better understanding the basic mechanisms involved in IR-adaptive resistance in MEC cell lines and how to efficiently overcome this critical problem
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