Effect of the Microstructure of Copper Films on the Damping of Oscillating Quartz Resonators*

An electrochemical procedure is described which allows the preparation of copper films of various crystallinity. Impedance spectra recorded for copper loaded quartz resonators were analysed in terms oft he lumped-element circuit of the Butterworth-Van Dyke type to obtain their electrical and mechanical properties. Plots of the damping resistance versus film thickness indicate that the film's dissipation factor is significantly smaller in the case of disordered films with a finer crystallinity (10—100nm) than in the case of more ordered structures having a grain size between 600—1500nm. This observations states, that the finely structured copper phase behaves more rigid than the coarse material. The suggested explanation relates this effect to energy losses which occur during oscillation at the phase boundary of the grains by wearless internal friction. No contributions to the damping from surface roughness were observed for films thicker 0.5pm. Thus, the damping of the quartz oscillator caused by different degrees of surface roughness of the generated copper films was of secondary importance, compared with the effect of the crystallinity

Circadian Rhythms of Fetal Liver Transcription Persist in the Absence of Canonical Circadian Clock Gene Expression Rhythms In Vivo

The cellular circadian clock and systemic cues drive rhythmicity in the transcriptome of adult peripheral tissues. However, the oscillating status of the circadian clocks in fetal tissues, and their response to maternal cues, are less clear. Most clock genes do not cycle in fetal livers from mice and rats, although tissue level rhythms rapidly emerge when fetal mouse liver explants are cultured in vitro. Thus, in the fetal mouse liver, the circadian clock does not oscillate at the cellular level (but is induced to oscillate in culture). To gain a comprehensive overview of the clock status in the fetal liver during late gestation, we performed microarray analyses on fetal liver tissues. In the fetal liver we did not observe circadian rhythms of clock gene expression or many other transcripts known to be rhythmically expressed in the adult liver. Nevertheless, JTK_CYCLE analysis identified some transcripts in the fetal liver that were rhythmically expressed, albeit at low amplitudes. Upon data filtering by coefficient of variation, the expression levels for transcripts related to pancreatic exocrine enzymes and zymogen secretion were found to undergo synchronized daily fluctuations at high amplitudes. These results suggest that maternal cues influence the fetal liver, despite the fact that we did not detect circadian rhythms of canonical clock gene expression in the fetal liver. These results raise important questions on the role of the circadian clock, or lack thereof, during ontogeny

Determination of the electromechanical parameters of the electrochemical quartz crystal microbalance

In this work we present a simple mechanical/electrical model for the electrochemical quartz crystal microbalance (EQCM). It consists of a harmonic oscillator (effective mass equal to one half of the crystal mass) coupled to an elastic element and in contact with a viscous fluid. As its electrical analog we consider a RLC series circuit. Simple arguments based on energy/power relationships lead to an easy identification of the mechanical parameters with the electrical ones. That identification together with considerations of the parallel capacitance effects of the electrodes allow us to test/calibrate an EQCM and also to interpret quartz crystal impedance-analyzer results. Model predictions are consistent with the experimental values. This is a subject of considerable relevance for all EQCM experiments. (C) 1998 Elsevier Science Ltd. All rights reserved.444170026326

Structure and activity relations in the hydrogen peroxide reduction at silver electrodes in alkaline NaF/NaOH electrolytes

The electrochemical interface between polycrystalline silver and alkaline NaF/NaOH electrolytes at various pH values has been studied by means of cyclic voltammetry and ac-impedance spectroscopy. Hydroxide electrochemisorption has been observed in a wide potential range (between −1.1 and 0 V SCE depending upon pH). Study of the hydrogen peroxide reduction at silver rotating-disc electrodes in alkaline NaF/NaOH electrolytes has proved the existence of a slow chemical step in the reaction mechanism, its rate being strongly affected by the submonolayer surface oxidation. The reaction scheme is proposed for the hydrogen peroxide reduction, which takes into consideration the structure of the adsorbate layer at the electrode/electrolyte interface at the variable potential

Determination of the electromechanical parameters of the electrochemical quartz crystal microbalance

In this work we present a simple mechanical/electrical model for the electrochemical quartz crystal microbalance (EQCM). It consists of a harmonic oscillator (effective mass equal to one half of the crystal mass) coupled to an elastic element and in contact with a viscous fluid. As its electrical analog we consider a RLC series circuit. Simple arguments based on energy/power relationships lead to an easy identification of the mechanical parameters with the electrical ones. That identification together with considerations of the parallel capacitance effects of the electrodes allow us to test/calibrate an EQCM and also to interpret quartz crystal impedance–analyzer results. Model predictions are consistent with the experimental values. This is a subject of considerable relevance for all EQCM experiments

Le zona ophtalmique et ses complications (prise en charge thérapeutique et prévention)

BORDEAUX2-BU Santé (330632101) / SudocSudocFranceF

Electrocatalytic Reduction of Peroxodisulfate in 0.5 M NaOH at Copper Electrodes. A Combined Quartz Microbalance and Rotating Ring/Disc Electrode Investigation

From an electrochemical investigation by means of an electrochemical quartz microbalance, a rotating disc electrode, and a ring/disc electrode, two mechanisms for the reduction of S2O82- became apparent. Besides the well-known outer-sphere cathodic reduction, a catalytic mechanism of S2O82- reduction operates in a potential range between the surface oxide region (≈-0.5 V/SCE) and -1.0 V/SCE. It involves the chemical oxidation of the copper surface to a soluble Cu(I) species. The catalytic mechanism is concluded to result from the specific interaction between S2O82- and the Cu surface modified by the presence of subsurface oxygen

Electrocatalytic Reduction Of Peroxodisulfate In 0.5 M Naoh At Copper Electrodes. A Combined Quartz Microbalance And Rotating Ring/disc Electrode Investigation

From an electrochemical investigation by means of an electrochemical quartz microbalance, a rotating disc electrode, and a ring/disc electrode, two mechanisms for the reduction of S2O82- became apparent. Besides the well-known outer-sphere cathodic reduction, a catalytic mechanism of S2O82- reduction operates in a potential range between the surface oxide region (≈-0.5 V/SCE) and -1.0 V/SCE. It involves the chemical oxidation of the copper surface to a soluble Cu(I) species. The catalytic mechanism is concluded to result from the specific interaction between S2O82- and the Cu surface modified by the presence of subsurface oxygen.1011424112414Frumkin, A.N., (1933) Z. Phys. Chem. (Munich), 164, p. 121Wolf, W., Ye, J., Purgand, M., Eiswirth, M., Doblhofer, K., (1992) Ber. Bunsen-Ges. Phys. Chem., 96, p. 1797Flätgen, G., Krischer, K., Ertl, G., (1995) Z. Naturforsch., 50 A, p. 1097Flätgen, G., Krischer, K., (1995) J. Chem. Phys., 103, p. 5428Flätgen, G., Krischer, K., Pettinger, B., Doblhofer, K., Junkes, H., Ertl, G., (1995) Science, 269, p. 668Flätgen, G., Krischer, K., (1995) Phys. Rev. E, 51, p. 3997Flätgen, G., Krischer, K., Ertl, G., J. Electroanal. Chem., , in pressKoper, M.T.M., (1996) Ber. Bunsen-Ges. Phys. Chem., 100, p. 497Damaskin, B.B., Safonov, V.A., Fedorovich, N.V., (1993) J. Electroanal. Chem., 349, p. 1Latimer, W.M., (1952) The Oxidation States of the Elements and Their Potentials in Aqueous Solutions, , Prentice-Hall: New YorkLevie, M.G., Migliorini, E., Ercolini, G., (1908) Gazz. Chim. Ital., 38, p. 583Bond, G.C., Hill, G.M., Tennison, R., (1959) J. Chem. Soc., p. 33Müller, L., (1967) J. Electroanal. Chem., 13, p. 275Müller, L., Wetzel, R., Otto, H., (1970) J. Electroanal. Chem., 24, p. 175Mark, H.B., Anson, F.C., (1963) J. Electroanal. Chem., 6, p. 251Burke, L.D., O'Sullivan, J.F., O'Dwyer, K.J., Scannell, R.A., Ahern, M.J.G., McCarthy, M.M., (1990) J. Electrochem. Soc., 137, p. 2476Desilvestro, J., Weaver, M.J., (1987) J. Electroanal. Chem., 234, p. 237Ye, J., Wolf, W., Doblhofer, K., Eiswirth, M., (1994), Unpublished work. Wolf, W. Ph.D. Thesis, Frei Universität Berlin, BerlinHärtinger, S., Pettinger, B., Doblhofer, K., (1995) J. Electroanal. Chem., 397, p. 335Soares, D.M., (1993) Meas. Sci. Technol., 4, p. 549Fruböse, C., Doblhofer, K., Soares, D.M., (1993) Ber. Bunsen-Ges. Phys. Chem., 97, p. 475Sauerbrey, G., (1959) Z. Phys., 155, p. 206Albery, W.J., Bruckenstein, S., (1966) Trans. Faraday Soc., 62, p. 1920Ikemiya, N., Kubo, T., Hara, S., (1995) Surf. Sci., 323, p. 81Strehblow, H.H., Titze, B., (1980) Electrochim. Acta, 25, p. 839Shirkhanzadeh, M., Thompson, G.E., Ashworth, V., (1990) Corr. Sci., 31, p. 293Miller, B., (1969) J. Electrochem. Soc., 116, p. 1675Tindall, G.W., Bruckenstein, S., (1969) J. Electroanal. Chem., 22, p. 367Schubert, H., Tegetmeyer, U., Schlögl, R., (1994) Cat. Lett., 28, p. 383Schedl-Niedrig, T., Bao, X., Muhler, M., Neisius, T., Schlögl, R., (1995) Annual Fachbeirat of Fritz-Haber-Institut of the Max-Planck-Gesellschaft, , Abstract AC12, BerlinWerner, H., Demuth, D., Schubert, H., Weinberg, G., Braun, T., Herein, D., Schlögl, R., (1995) Annual Fachbeirat of Fritz-Haber-Institut of the Max-Planck-Gesellschaft, , Abstract AC13, BerlinPolak, M., (1994) Surf. Sci., 321, p. 249Carley, A.F., Davies, P.R., Roberts, M.W., Vicent, D., (1994) Top. Catal., 1, p. 35Davies, P.R., Roberts, M.W., Shukla, N., Vicent, D., (1995) Surf. Sci., 325, p. 5

An Eqcm Study Of The Electrochemical Copper(ii)/copper(i)/copper System In The Presence Of Peg And Chloride Ions

The charge-transfer reaction between copper(II) and copper electrodes is studied in electrolytes that are similar to galvanic copper baths, 2.2 M H 2SO4 + 0.3 M CuSO4 + chloride ions (c cl ≤ 1 × 10-2 M), and polyethyleneglycol 1500 (PEG, cPEG ≤ 4 × 10-3 M). Electrochemical quartz crystal microbalance (EQCM) measurements are conducted, mainly under conditions of cyclic voltammetry. The formation and dissolution of CuCl on the electrode surface at ccl ≥ 2 mM is demonstrated, a notable shift of the pseudo-equilibrium potential associated with CuCl deposition is analyzed, and the inhibition of the charge-transfer reaction by the PEG/Cl- surface layer is characterized. It is shown that the inhibiting layer forms by reaction between the adsorbate-covered copper electrode and PEG, i.e., neither Cu+ nor Cu++ from the electrolyte are required. Numerical simulations of the processes as well as parallel experiments conducted with electrolytes not containing Cu(II) support the proposed mechanisms, in particular the role of the intermediate Cu+. © 2003 The Electrochemical Society. All rights reserved.15010C657C664Schlesinger, M., Paunovic, M., (2000) Modern Electroplating, 4th Ed., , Editors, Chap. 2, John Wiley & Sons, Inc., New York(1988) Taschenbuch für Galvanotechnik, 1, pp. 150-162. , Verfahrenstechnik, LPW-Chemie GMBH, 13. AusgabeHealy, J.P., Pletcher, D., Goodenough, M., (1992) J. Electroanal. Chem., 338, p. 155Goldbach, S., Messing, W., Daenen, T., Lapicque, F., (1998) Electrochim. Acta, 44, p. 323Soares, D.M., Wasle, S., Doblhofer, K., Tenan, M.A., (2002) Chem. Phys. Chem., 3, p. 817Soares, D.M., Wasle, S., Weil, K.G., Doblhofer, K., (2002) J. Electroanal. Chem., 532, p. 353Doblhofer, K., Soares, D., Wasle, S., Weil, K.G., Weinberg, G., Ertl, G., (2003) Z. Phys. Chem. (Munich), 217, p. 1Stoychev, D., (1998) Trans Inst. Met. Finish., 76, p. 73Jovic, V.D., Jovic, B.M., (2001) J. Serb. Chem. Soc., 66, p. 935Steppan, J.J., Hall, L.C., Roth, J.A., (1991) J. Electrochem. Soc., 138, p. 2635Chu, A.K.P., Sukava, A.J., (1969) J. Electrochem. Soc., 116, p. 1188Kelly, J.J., West, A.C., (1998) J. Electrochem. Soc., 145, p. 3472Yokoi, M., Konishi, S., Hayashi, T., (1983) Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 51, p. 460Yokoi, M., Konishi, S., Hayashi, T., (1984) Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 52, p. 218Li, Y.J., Oslonovich, J., Mazouz, N., Plonge, F., Krischer, K., (2001) Science, 291, p. 2395Mattsson, E., Bockris, J.O'M., (1959) Trans. Faraday Soc., 55, p. 1586Nekrasov, L.N., Berezina, N.P., (1962) Dokl: Akad. Nauk SSSR, 142, p. 855Molodov, A.I., Markosyan, G.N., Losev, V.V., (1972) Electrochim. Acta, 17, p. 701Bard, A.J., (1974) Encyclopedia of Electrochemistry of the Elements, 2, p. 384. , Marcel Dekker, Inc., New YorkBagotzky, V.S., (1993) Fundamentals of Electrochemistry, , Chap. 13, Plenum Press, New York, Translated from Russian by K. MüllerSnook, G.A., Bond, A.M., Fletcher, S., (2002) J. Electroanal. Chem., 526, p. 1Mo, Y., Hwang, E., Scherson, D., (1996) J. Electrochem. Soc., 143, p. 37Vaskelis, A., Stalnionis, G., Jusy, Z., (1999) J. Electroanal. Chem., 465, p. 142Jusy, Z., Stalnionis, G., (2000) Electrochim. Acta, 45, p. 3675Inzelt, G., (1993) J. Electroanal. Chem., 348, p. 465Wiese, H., Weil, K.G., (1987) Ber. Bunsenges. Phys. Chem., 91, p. 619Láng, G.G., Ujvári, M., Horányi, G., (2002) J. Electroanal. Chem., 522, p. 179Braun, M., Nobe, K., (1979) J. Electrochem. Soc., 126, p. 1666Moreau, A., Frayret, J.P., Del Rey, F., Pointeau, R., (1982) Electrochim. Acta, 27, p. 1281Itagaki, M., Tagaki, M., Watanabe, K., (1996) Corros. Sci., 38, p. 1109Itagaki, M., Tagaki, M., Watanabe, K., (1997) J. Electroanal. Chem., 440, p. 139Hauser, A.K., Newman, J., (1989) J. Electrochem. Soc., 136, p. 3249Gabrielli, C., Keddam, M., Minouflet-Laurent, F., Perrot, H., (2000) Electrochem. Solid-state Lett., 3, p. 418Lee, H.P., Nobe, K., Pearlstein, A.J., (1985) J. Electrochem. Soc., 132, p. 1031Lee, H.P., Nobe, K., Pearlstein, A.J., (1986) J. Electrochem. Soc., 133, p. 2035Fahidy, T.Z., Gu, Z.H., (1995) Modern Aspects of Electrochemistry, 27, p. 384. , R. E. White, J. O'M. Bockris, and B. E. Conway, Editors, Plenum Press, New YorkSoares, D.M., (1993) Meas. Sci. Technol., 4, p. 543Glasstone, S., Laidler, K.J., Eyring, H., (1941) The Theory of Rate Processes, , Chap. 10, MCGraw-Hill Book Company, Inc., New YorkRobinson, R.A., Stokes, R.H., (1949) Trans. Faraday Soc., 45, p. 612Kolthoff, I.M., Lingane, J.J., (1965) Polarography, 2, p. 494. , New Yor