排序方式: 共有125条查询结果,搜索用时 31 毫秒
101.
Soner Buytoz Fethi Dagdelen Serkan Islak Mediha Kok Durmus Kir Ercan Ercan 《Journal of Thermal Analysis and Calorimetry》2014,117(3):1277-1283
Copper matrix with an individual addition of TiC particles was prepared by means of powder metallurgy and hot pressing process, and the effect of TiC addition on microstructure, thermal properties, and electrical conductivity of Cu–TiC composites was investigated. The TiC quantity was changed as 1, 3, 5, 10, and 15 Cu (in mass%), and Cu–TiC powder mixtures were hot-pressed for 4 min at 700 °C under an applied pressure of 50 MPa. Microstructure studies revealed that TiC particles were distributed uniformly in the Cu matrix. Thermal Analysis result showed that there were two exothermic peaks and with rising TiC rate, oxidation amount of Cu composite decreased. With the increasing addition of TiC, hardness of composites changed between 58.6 HV0.1 and 87.8 HV0.1. The highest electrical conductivity for Cu–TiC composites was obtained in the Cu-1 mass% TiC composite, with approximately 81.2 % IACS. 相似文献
102.
Quantitation of Cu+‐catalyzed Decomposition of S‐Nitrosoglutathione Using Saville and Electrochemical Detection: a Pronounced Effect of Glutathione and Copper Concentrations
下载免费PDF全文
![点击此处可从《Electroanalysis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Abdulghani Ismail Sophie Griveau Fanny d'Orlyé Anne Varenne Fethi Bedioui 《Electroanalysis》2015,27(12):2857-2863
S‐nitrosothiols (RSNOs) are composed of nitric oxide (NO) bound to the sulfhydryl group of amino acids of peptides or proteins. There is a great interest for their quantitation in biological fluids as they have a crucial impact on physiological and pathophysiological events. Most analytical methodologies for quantitation of RSNOs are based on their decomposition followed by the detection of the released NO. In order to obtain the optimal sensitivity for each detection method, the total decomposition of RSNOs is highly desired. The decomposition of RSNOs can be obtained by using catalytically active metal ions, such as Cu+, obtained from CuSO4 in presence of a reducing agent such as glutathione (GSH) that is naturally present in biological environment. In this work, we have re‐investigated the decomposition of S‐nitrosoglutathione (GSNO) which is the most abundant in vivo low molecular weight RSNO, with a special emphasis on the effect of CuSO4, GSH, and GSNO concentrations and of their ratio. To this aim, GSNO decomposition optimization was performed by both indirect (Griess assay) and direct (real time electrochemical detection of NO at NO‐microsensor) quantitation methods. Our results show that the ratio between CuSO4, GSH and GSNO should be adjusted to tune the highest decomposition rate of GSNO and the most efficient electrochemical detection of released NO; also it shows the deleterious effect of very high GSH concentration on the detection of GSNO. 相似文献
103.
We have studied structural, electronic, elastic and dynamical properties of NiSi2 by employing the plane wave pseudopotential method based on density functional theory within the local density approximation. The calculated lattice constant, bulk modulus and first-order pressure derivative of the bulk modulus are reported and compared with earlier available experimental and theoretical calculations. Numerical first-principles calculations of the elastic constants were used to calculate C11, C12 and C44 for NiSi2. The calculated electronic band structure has been compared with angle-resolved photoemission spectroscopy experimental data along the [100] and [111] symmetry directions. A linear response approach to density functional theory is used to derive the phonon dispersion curves and phonon partial density of states. Atomic displacement patterns for NiSi2 at the Γ, X and L symmetry points are also presented. 相似文献
104.
Fethi Soltani 《Complex Analysis and Operator Theory》2014,8(1):311-325
We give an application of the theory of reproducing kernels to the Tikhonov regularization on the Sobolev spaces associated with a singular second-order differential operator. Next, we come up with some results regarding the multiplier operators for the Sturm–Liouville transform. 相似文献
105.
Fethi Soltani 《Complex Analysis and Operator Theory》2016,10(7):1501-1517
In this work, we recall some properties of the generalized Fock space \(F_k(\mathbb {C})\) and the Hilbert space \(H_k(\mathbb {C})\) (defined by the squared norm \(\Vert f\Vert ^2_{H_k(\mathbb {C})}:=\Vert f\Vert ^2_{F_k(\mathbb {C})}+\langle zf',f\rangle _{F_k(\mathbb {C})}\)). Next, we give the best approximation of the bounded operators \(L:F_k(\mathbb {C})\rightarrow H_k(\mathbb {C})\). As applications, we come up with some results regarding the approximate formulas for the difference operator, the Dunkl difference operator and the primitive operator. 相似文献
106.
Aisha Attar Fethi Achi Saliha Bourouina Bacha Mustapha Bourouina Laura Cubillana-Aguilera 《International journal of environmental analytical chemistry》2016,96(6):515-529
A novel inhibition biosensor used for the detection of sulphides (Na2S) has been developed. The biosensor is based on the immobilisation of horseradish peroxidase (HRP) on the Sonogel-Carbon (SNGC) electrode using glutaraldehyde, Poly(4-vinylpyridine) and gold sononanoparticles (AuSNPs). The Poly(4-vinylpyridine) was used due to its high affinity for sulphide anions, while the presence of gold sononanoparticles enhances the electron transfer reaction and improves the analytical performance of the biosensor. The amperometric measurements were performed at an applied potential of ?0.15 V vs. Ag/AgCl in 50 mM sodium acetate buffer solution pH = 6.0. The apparent kinetic parameters (Kmapp, Vmax) of immobilised HRP were calculated in the absence of inhibitor (sulphide) using caffeic acid as substrate. Under the optimal experimental conditions, the determination of sulphide can be achieved in a dynamic range of 0.4–2.8 µM with a low limit of detection of 0.15 µM. The electrochemical impedance spectroscopy (EIS) was also used to characterise the interactions of substrate and inhibitor with the enzyme-modified electrode. The developed biosensor exhibited high sensitivity, selectivity and stability, and can be successfully applied to the detection of sulphide in water. 相似文献
107.
108.
Fungisai Matemadombo Sophie Griveau Fethi Bedioui Tebello Nyokong 《Electroanalysis》2008,20(17):1863-1872
Manganese phthalocyanine MnPc(SPh)4 has been synthesized and used to form self assembled monolayers on gold electrodes. The well packed SAM monolayer was characterized by analyzing the blocking of a number of Faradic processes by cyclic voltammetry, evaluating the electrical characteristics of the modified electrode by electrochemical impedance and imaging the modified surface by electrochemical scanning microscopy. Finally, MnPc(SPh)4‐SAM modified electrode displayed an electrocatalytic behavior toward the oxidation of nitrite. 相似文献
109.
Jan A. Claußen Gonzalo Ochoa Maritza Páez Juan Costamagna Miguel Gulppi Tebello Nyokong Fethi Bedioui José H. Zagal 《Journal of Solid State Electrochemistry》2008,12(5):473-481
We have investigated the electrocatalytic activity of several substituted and unsubstituted cobalt–phthalocyanines of substituted
tetraphenyl porphyrins and of vitamin B12, for the electro-oxidation of 2-mercaptoacetate, with the complexes pre-adsorbed on a pyrolytic graphite electrode. Several
N4-macrocyclic were used to have a wide variety of Co(II)/(I) formal potentials. The electrocatalytic activity, measured as
current at constant potential, increases with the Co(II)/(I) redox potential for porphyrins as Co–pentafluorotetraphenylporphyrin < Co–tetrasulfonatotetraphenylporphyrin < Co-2,2′,2″,2‴tetra-aminotetraphenylporphyrin
and decreases for cobalt phthalocyanines as Co-3,4-octaethylhexyloxyphthalocyanine > Co–octamethoxyphthalocyanine > Co–tetranitrophthalocyanine
Co–tetraaminophthalocyanine > Co–unsubstituted phthalocyanine > Co–tetrasulfonatophthalocyanine > Co–perfluorinated phthalocyanine.
Vitamin B12 exhibits the maximum activity. A correlation of log I (at constant potential) versus the Co(II)/(I) formal potential of the catalysts gives a volcano curve. This clearly shows
that the search for better catalysts for this reaction point to those N4-macrocyclic complexes with Co(II)/(I) formal potentials close to −0.84 V versus SCE, which correspond to an optimum situation
for the interaction of the thiol with the active site.
Dedicated to Prof. Dr. Teresa Iwasita on the occasion of her 65th birthday in recognition of her numerous contributions to
interfacial electrochemistry. 相似文献
110.
Bedioui F Griveau S Nyokong T Appleby AJ Caro CA Gulppi M Ochoa G Zagal JH 《Physical chemistry chemical physics : PCCP》2007,9(26):3383-3396
In this work we discuss different approaches for achieving electrodes modified with N(4) macrocyclic complexes for the catalysis of the electrochemical oxidation of thiols. These approaches involve adsorption, electropolymerization and molecular anchoring using self assembled monolayers. We also discuss the parameters that determine the reactivity of these complexes. Catalytic activity is associated with the nature of the central metal, redox potentials and Hammett parameters of substituents on the ligand. Correlations between catalytic activity (log i at constant E) and the redox potential of catalysts for complexes of Cr, Mn, Fe, Co, Ni and Cu are linear with an increase of activity for more positive redox potentials. For a great variety complexes bearing the same metal center (Co) correlations between log i and E(o') of the Co(II)/Co(I) couple have the shape of an unsymmetric volcano. This indicates that the potential of the Co(II)/Co(I) couple can be tuned using the appropriate ligand to achieve maximum catalytic activity. Maximum activity probably corresponds to a DeltaG of adsorption of the thiol on the Co center equal to zero, and to a coverage of active sites by the thiol equal to 0.5. 相似文献