scholarly journals The electro-oxidation of the mixture of formaldehyde and 2-propanol on gold (100) and (111) single crystal planes in alkaline medium

2000 ◽  
Vol 65 (12) ◽  
pp. 915-922 ◽  
Author(s):  
Tanja Vidakovic ◽  
Milka Avramov-Ivic ◽  
Branislav Nikolic

The effect of formaldehyde on the oxidation of 2-propanol and vice versa on gold single crystal planes (100 and 111) was studied. An activating effect in the reaction of the simultaneous oxidation of 2-propanol and formaldehyde was obtained on a gold (100) plane. In the case of a gold (111) electrode, the activation effect was not obtained. It was concluded that the adsorption of formaldehyde on the electrode surface prevents the adsorption of poisoning species formed during the electro-oxidation of 2-propanol on the Au(100) plane, while this is not the case on the Au(111) plane. The different behaviour is caused by the difference in the symmetry of the surface atoms of these two Au single-crystal planes.

2000 ◽  
Vol 104 (28) ◽  
pp. 6642-6652 ◽  
Author(s):  
W. F. Lin ◽  
P. A. Christensen ◽  
A. Hamnett ◽  
M. S. Zei ◽  
G. Ertl

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
O. N. Senkov ◽  
D. B. Miracle

AbstractTwo classical criteria, by Pugh and Pettifor, have been widely used by metallurgists to predict whether a material will be brittle or ductile. A phenomenological correlation by Pugh between metal brittleness and its shear modulus to bulk modulus ratio was established more than 60 years ago. Nearly four decades later Pettifor conducted a quantum mechanical analysis of bond hybridization in a series of intermetallics and derived a separate ductility criterion based on the difference between two single-crystal elastic constants, C12–C44. In this paper, we discover the link between these two criteria and show that they are identical for materials with cubic crystal structures.


Author(s):  
R.M. Abdel Hameed ◽  
Ibrahim M.A. Mohamed ◽  
Abdullah M. Al-Enizi ◽  
Ahmed Abutaleb ◽  
Shoyebmohamad F. Shaikh ◽  
...  

2016 ◽  
Vol 7 (4) ◽  
pp. 297-304 ◽  
Author(s):  
E. H. Fontes ◽  
Sirlane G. da Silva ◽  
E. V. Spinace´ ◽  
A. O. Neto ◽  
R. F. B. de Souza

2016 ◽  
Vol 193 ◽  
pp. 99-112 ◽  
Author(s):  
Ling Zhang ◽  
Jens Ulstrup ◽  
Jingdong Zhang

DNA quadruplexes (qs) are a class of “non-canonical” oligonucleotides (OGNs) composed of stacked guanine (G) quartets stabilized by specific cations. Metal porphyrins selectively bind to G-qs complexes to form what is known as DNAzyme, which can exhibit peroxidase and other catalytic activity similar to heme group metalloenzymes. In the present study we investigate the electrochemical properties and the structure of DNAzyme monolayers on single-crystal Au(111)-electrode surfaces using cyclic voltammetry and scanning tunnelling microscopy under electrochemical potential control (in situ STM). The target DNAzyme is formed from a single-strand OGN with 12 guanines and iron(iii) porphyrin IX (hemin), and assembles on Au(111) through a mercapto alkyl linker. The DNAzyme monolayers exhibit a strong pair of redox peaks at 0.0 V (NHE) at pH 7 in acetate buffer, shifted positively by about 50 mV compared to free hemin weakly physisorbed on the Au(111)-electrode surface. The voltammetric hemin signal of DNAzyme is enhanced 15 times compared with that of hemin adsorbed directly on the Au(111)-electrode surface. This is indicative of both the formation of a close to dense DNAzyme monolayer and that hemin is strongly bound to the immobilized 12G-qs in well-defined orientation favorable for interfacial ET with a rate constant of 6.0 ± 0.4 s−1. This is supported by in situ STM which discloses single-molecule G-quartet structures with a size of 1.6 ± 0.2 nm.


Author(s):  
M. Yu. Tashmetov ◽  
F. K. Khallokov ◽  
N. B. Ismatov ◽  
I. I. Yuldashova ◽  
S. Kh. Umarov

It is shown that the replacement of a part of sulfur atoms with selenium atoms in a TlInS2 single crystal stimulates the formation of a single-phase state with a monoclinic structure (space group [Formula: see text]/[Formula: see text] in TlInS[Formula: see text]Se[Formula: see text] ([Formula: see text]). Irradiation with 2 MeV electrons and a fluence of [Formula: see text] electron/cm2 of powder TlInS[Formula: see text]Se[Formula: see text] ([Formula: see text]) leads to an increase in the crystallite size from 56.5 nm to 65 nm, which is most likely associated with a decrease in the interface. The difference between the surface morphology of the synthesized TlInS[Formula: see text]Se[Formula: see text] ([Formula: see text]) single crystal and the surface morphology of the TlInS2 single crystal is established, which consists in a decrease in the height and width of the roughness in TlInS[Formula: see text]Se[Formula: see text] ([Formula: see text]). Irradiation of a TlInS[Formula: see text]Se[Formula: see text] ([Formula: see text]) single crystal with electrons with a fluence of [Formula: see text] electron/cm2 does not lead to a change in the height of the tubercle on its surface, and the average value of its width increases more than ten-fold. The identity of the peaks in the Raman spectra of the TlInS[Formula: see text]Se[Formula: see text] ([Formula: see text]) single crystal before and after its irradiation with electrons with an energy of 2 MeV and upto a fluence of [Formula: see text] electron/cm2, along with the absence of a shift of the peaks, indicates the radiation resistance of the TlInS[Formula: see text]Se[Formula: see text] ([Formula: see text]) single crystal.


2017 ◽  
Vol 202 ◽  
pp. 95-103 ◽  
Author(s):  
A. Cuña ◽  
C. Reyes Plascencia ◽  
E.L. da Silva ◽  
J. Marcuzzo ◽  
S. Khan ◽  
...  

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