Browsing by Subject "copper"

Article

Activated biochar derived from cactus fibres - Preparation, characterization and application on Cu(II) removal from aqueous solutions

Hadjittofi, Loukia; Prodromou, Melpomeni; Pashalidis, Ioannis (2014)

The adsorption efficiency of activated biochar prepared from cactus fibres regarding the removal of Cu(II) from aqueous solutions has been investigated as a function of various physicochemical parameters (e.g. pH, initial ...

Article

Authenticity of the traditional Cypriot spirit "zivania" on the basis of metal content using a combination of coupled plasma spectroscopy and statistical analysis

Kokkinofta, Rebecca I.; Petrakis, Panos V.; Mavromoustakos, Thomas M.; Theocharis, Charis R. (2003)

Sixty-eight alcoholic beverages ranging in alcoholic degree between 40 and 55 from different countries were analyzed for their 16 most abundant metal elements using inductively coupled plasma (ICP) spectroscopy. The results ...

Article

Competitive sorption of Cu(II), Eu(III) and U(VI) ions on dunite in aqueous solutions: A potentiometric study

Konstantinou, M.; Pashalidis, Ioannis (2010)

The competitive sorption of Cu(II), Eu(III) and U(VI)) ions in aqueous solutions by dunite, has been investigated by potentiometry at pH 6, I = 0.1 M NaClO4 and 25°C. Numerical analysis of the experimental data supports ...

Article

Competitive sorption of Cu(II), Eu(III) and U(VI) ions on TiO2 in aqueous solutions-A potentiometric study

Konstantinou, M.; Pashalidis, Ioannis (2008)

The competitive sorption of Cu(II), Eu(III) and U(VI) ions in aqueous solutions by TiO2, has been investigated by potentiometry at I = 0.1 M NaClO4, 25 °C and under atmospheric conditions. For Cu(II) ions the investigation ...

Article

The Conversion of 4-Anilinoquinazoline- and 3-Aryl-4-imino-3,4-dihydro-quinazoline-2-carbonitriles into Benzo[4,5]imidazo[1,2-c]quinazoline-6-carbonitriles via Oxidative and Nonoxidative C-N Couplings

Mirallai, Styliana I.; Koutentis, Panayiotis Andreas (2015)

Benzo[4,5]imidazo[1,2-c]quinazoline-6-carbonitriles are prepared in high yields via three new routes: (1) a Cu(OTf)2 (0-5 mol %) catalyzed hypervalent iodine [PhI(OTf)2] mediated oxidative coupling of 4-anilinoquinazolin ...

Article

Detection of the His-heme Fe2+-NO species in the reduction of NO to N2O by ba3-oxidase from thermus thermophilus

Pinakoulaki, Eftychia; Ohta, T.; Soulimane, T.; Kitagawa, T.; Varotsis, Constantinos (2005)

Reaction pathways in the enzymatic formation and cleavage of the N-N and N-O bonds, respectively, are difficult to verify without the structure of the intermediates, but we now have such information on the heme a3 2+-NO ...

Article

Direct detection of Fe(IV)=O intermediates in the cytochrome aa3 oxidase from Paracoccus denitrificans[H2O2 reaction

Pinakoulaki, Eftychia; Pfitzner, U.; Ludwig, B.; Varotsis, Constantinos (2003)

We report the first evidence for the formation of the "607- and 580-nm forms" in the cytochrome oxidase aa3/H2O2 reaction without the involvement of tyrosine 280. The pKa of the 607-580-nm transition is 7.5. The 607-nm ...

Article

Highly efficient spin filtering of ballistic electrons

Steinmuller, S. J.; Trypiniotis, Theodossis; Cho, W. S.; Hirohata, A.; Lew, W. S.; Vaz, C. A. F.; Bland, J. A. C. (2004)

Spin dependent electron transport in hybrid Au/Co/Cu/NiFe/n-GaAs spin valve Schottky barrier structures was investigated using photoexcitation at various wavelengths. For excitation with the photon energy well above the ...

Article

Hydrophilic olive cake extracts: Characterization by physicochemical properties and Cu(II) complexation

Kolokassidou, K.; Szymczak, W.; Wolf, M.; Obermeier, C.; Buckau, G.; Pashalidis, Ioannis (2009)

Disposed olive cake generates hydrophilic components that can be mobilized in the aquatic environment. This paper deals with the characterization of such components, isolated by alkaline extraction. It is shown that these ...

Article

Near critical behavior in the two-dimensional spin-gap system SrCu2(BO3)2

Zorko, A.; Arčon, D.; Lappas, A.; Giapintzakis, John (2002)

The temperature dependence of the powdered X-band ESR spectra has been measured in a two-dimensional spin-gap system SrCu2(BO3)2 in the temperature range between 5 and 300 K. The spectra are composed of two overlapping ...

Article

Nitric oxide activation and reduction by heme-copper oxidoreductases and nitric oxide reductase

Pinakoulaki, Eftychia; Varotsis, Constantinos (2008)

The understanding of the dynamics and conformational control involved in the interplay between structure and function of nitric oxide reductase (Nor) and heme-copper oxidoreductases in their function to convert nitric oxide ...

Article

The origin of the Fe IV = O intermediates in cytochrome aa 3 oxidase

Pinakoulaki, Eftychia; Daskalakis, Vangelis; Varotsis, Constantinos (2012)

The dioxygen reduction mechanism in cytochrome oxidases relies on proton control of the electron transfer events that drive the process. Proton delivery and proton channels in the protein that are relevant to substrate ...

Article

Probing the nitrite and nitric oxide reductase activity of cbb3 oxidase: Resonance Raman detection of a six-coordinate ferrous heme-nitrosyl species in the binuclear b3/CuB center

Loullis, Andreas; Pinakoulaki, Eftychia (2015)

In this work we report the first spectroscopic evidence demonstrating that cbb3 oxidase catalyzes the reduction of nitrite to nitrous oxide under reducing anaerobic conditions. The reaction proceeds through the formation ...

Article

Reactivation of an aged commercial three-way catalyst by oxalic and citric acid washing

Christou, Stavroula Y.; Birgersson, H.; Fierro, José Luis García; Efstathiou, Angelos M. (2006)

The efficiency of dilute oxalic and citric acid solutions on improving the oxygen storage capacity (OSC) and catalytic activity of a severely aged (83 000 km) commercial three-way catalyst (TWC) has been investigated. ...

Article

Regeneration of three-way automobile catalysts using biodegradable metal chelating agent-S, S-ethylenediamine disuccinic acid (S, S-EDDS)

Subramanian, B.; Christou, Stavroula Y.; Efstathiou, Angelos M.; Namboodiri, V.; Dionysiou, Dionysios Demetriou D. (2011)

Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S-ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel ...

Article

Resonance Raman detection of the Fe2+-C-N modes in heme-copper oxidases: A probe of the active site

Pinakoulaki, Eftychia; Vamvouka, M.; Varotsis, Constantinos (2004)

Resonance Raman spectroscopy has been employed to investigate the reduced cyano complexes of cytochrome aa3 from bovine heart and Rhodobacter sphaeroides and of cytochrome bo3 from E. coli. In the aa 3-type oxidases, the ...

Article

The role of the cross-link His-Tyr in the functional properties of the binuclear center in cytochrome c oxidase

Pinakoulaki, Eftychia; Pfitzner, U.; Ludwig, B.; Varotsis, Constantinos (2002)

Resonance Raman and Fourier transform infrared spectroscopies have been used to study the aa3-type cytochrome c oxidase and the Y280H mutant from Paracoccus denitrificans. The stability of the binuclear center in the absence ...

Article

Spectroscopic evidence for a pseudogap in the normal state of underdoped high-T(c) superconductors

Ding, H.; Yokoya, T.; Campuzano, Juan C.; Takahashi, T.; Randeria, M.; Norman, M. R.; Mochiku, T.; Kadowaki, K.; Giapintzakis, John (1996)

It is well known that BCS mean-field theory is remarkably successful in describing conventional superconductors. A central concept of BCS theory is the energy gap in the electronic excitation spectrum below the superconducting ...

Article

The structure of a ferrous heme-nitro species in the binuclear heme a3/CuB center of ba3-cytochrome c oxidase as determined by resonance Raman spectroscopy

Loullis, Andreas; Noor, M. R.; Soulimane, T.; Pinakoulaki, Eftychia (2015)

Members of the cytochrome c oxidase family exhibit nitrite reductase activity. In this work, we have characterized a ferrous heme a3-nitro species in ba3-oxidase by resonance Raman spectroscopy. This provides the first ...

Article

The structure of the hyponitrite species in a heme Fe-Cu binuclear center

Varotsis, Constantinos; Ohta, T.; Kitagawa, T.; Soulimane, T.; Pinakoulaki, Eftychia (2007)

NO laughing matter: The enzymatic production of laughing gas (N 2O) from two molecules of NO requires the formation of the N-N bond and the subsequent cleavage of the N-OH bond. Resonance Raman spectroscopic studies have ...