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EN
The inhibition of X80 carbon steel corrosion in 1 M HCl solution by dexketoprofen (DKP) was studied using weight loss (WL), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and scanning electron microscopy (SEM) techniques. The results indicated that DKP acts by way of adsorption as an effective protective inhibitor in the aggressive acid medium. The inhibition efficiency of DKP increased with concentration but was lower at higher temperature. The results of potentiodynamic polarization showed that DKP molecule behaved as a mixed type inhibitor by reducing both the anodic and the cathodic electrochemical reactions. Dexketoprofen was adsorbed on the X80 steel surface in accordance with Langmuir adsorption isotherm. SEM analyses supported formation of protective film on the X80 steel in the presence of DKP.
2
Content available remote Inactivation of cholinesterases by silver and gold ions in vitro
100%
Open Chemistry
|
2013
|
tom 11
|
nr 6
935-944
EN
The main goal of the present study was to investigate the effects of silver and gold ions on cholinesterases (ChEs) activity due to increasing application of these metals in a wide variety of nanomaterials. A chromogenic assay using the substrate o-nitrophenyl acetate/butyrate made it possible to conclude unmistakably that both metals inhibit ChEs. Addition of bovine serum albumin (BSA) indicates that binding of metal ions to albumin could serve to scavenge metals and consequently reduce their amount for reaction with ChEs. The effects of metal ions on ChE should be taken into consideration when using this enzyme as an environmental biomarker. [...]
EN
L-glycine and L-cysteine exhibit, strong inhibition of partial purified DIPHENOL OXIDASE at strawberry. The concentration of L-glycine inhibiting Diphenol oxidase activity by 50% (IC50) was 0.5 and 0.4 mM at pH 6.7 and 8, respectively. The inhibition of partial purified Diphenol oxidase activity is pH and inhibitor dependent. Kinetic studies indicate that L-glycine is a uncompetetive inhibitor and L-cysteine is competitive and noncompetitive inhibitor of Diphenol oxidase activity. Vmax and Km for catechol oxidation at pH 6.7 and in presence of L-glycine (1.4M) was 0.09 ∆A min-1 and 10 mM. Vmax for catechol oxidation at pH 8 and in absence of L-glycine was 0.09 ∆A min–1, with a Km of 3.5 mM. Kinetics parameters indicated the highest catalytic efficiency ( units mg–1 prot mM–1) with catechol and L-glycine at pH 8: 4 , then with L-cystein at pH 8: 1.7, L-glycine at pH 6.7: 1.4 and L-cystein at pH 6.7: 0.25.
4
100%
EN
The immobilisation of AChE enzyme through chemisorption on Au-modified graphite was examined with view of its prospective application in the design of membraneless electrochemical biosensors for the assay of enzyme inhibitors. The developed immobilisation protocol has been based on a two-stage procedure, comprising i) electrodeposition of gold nanostructures on spectroscopic graphite; followed by ii) chemisorption of the enzyme onto gold nanoparticles. Both the coverage of the electrode surface with Au nanostructures and the conditions for enzyme immobilisation were optimised. The proposed electrode architecture together with the specific type of enzyme immobilisation allow for a long-term retaining of the enzyme catalytic activity. The extent of inhibition of the immobilised acetylcholinesterase enzyme by the organophosphorous compound monocrotophos has been found to depend linearly on its concentration over the range from 50 to 400 nmol mL−1 with sensitivity 77.2% inhibition per 1 µmol mL−1 of monocrotophos. [...]
EN
The inhibitive action of phytic acid (PA) on Q235 mild steel corrosion in 1 M HCl environment was investigated using electrochemical techniques. Polarization results revealed PA to be a mixed- type inhibitor in 1 M HCl environment, while impedance results provide evidence of adsorption of the PA species on the corroding metal surface. The adsorption of PA obeyed Langmuir adsorption isotherm. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) studies all revealed the formation of a protective film adsorbed on the steel surface.
EN
The changes taking place with the corrosion-resistant coating, but not the state of the surface subjected to corrosion are investigated in this paper in contrast to traditional approaches. We used the method of nitrogen relaxometry NQR and multi-exponential inversion of decay of longitudinal and transverse components of the nuclear magnetization is applied for the first time for this purpose. The results of experimental studies of changes in the distributions of spin-spin and spin-lattice relaxation of crystallite powder of sodium nitrite and urotropin, the mixture of which is used as a corrosion inhibitor of ferrous metals are considered.
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