New synthesised pyridazine derivatives as effective inhibitors for the corrosion of pure iron in HCl medium

The inhibition of pure iron in 1 M HCl by new synthesised pyridazine compounds has been studied by weight loss, electrochemical polarisation and electrochemical impedance spectroscopy (EIS) measurements. The results obtained reveal that these compounds are efficient inhibitors. The inhibition efficiency increases with the increase of inhibitor concentration and reached 98% at 10⁻⁴ M for 5-benzyl-6-methyl pyridazine-3-thione. Potentiodynamic polarisation studies clearly reveal that the presence of pyridazines does not change the mechanism of hydrogen evolution and that they act essentially as cathodic inhibitors. The temperature effect on the corrosion behaviour of pure iron in 1 M HCl without and with the pyridazines at 10⁻⁴ M was studied in the temperature range from 298 to 353 K. EIS measurements show that the increase of the transfer resistance with the inhibitor concentration.     

Inhibition of pure iron by new synthesized tripyrazole derivatives in HCl solution

Inhibitory effect of some new synthesized tripyrazole compounds on corrosion of pure iron in 1 M HCl solution has been studied using weight-loss measurements and various electrochemical techniques polarization and impedance spectroscopy methods. The inhibiting action is more pronounced with N,N,N-tris[(3,5-dimethyl-1H-pyrazol-1-yl)methyl] amine (P1), and its inhibition efficiency increases with its concentration and attains the maximum value of 94% at the 2.5 × 10⁻⁴ M. The effect of temperature on the corrosion behaviour of iron was studied in the range from 298 to 353 K with and without P1 at 2.5 × 10⁻⁴ M. We note a good agreement between gravimetric and electrochemical methods potentiodynamic polarization and impedance spectroscopy (EIS). Polarization measurements show also that the compound acts mixed inhibitor. The catholic curves indicate that the reduction of proton at the pure iron surface happens within a pure activating mechanism. EIS measurements show the increase of the transfer resistance with the inhibitor concentration. The presence of the N,N,N-tris[(3,5-dimethyl-1H-pyrazol-1-yl)methyl] amine increases the inhibition efficiency and not caused a drastic change in its adsorption mechanism. The adsorption of P1 on the surface of iron in 1 M HCl obeys a Langmuir isotherm adsorption.     

Region-based facial representation for real-time Action Units intensity detection across datasets

Pattern Analysis and Applications - Most research on facial expressions recognition has focused on binary Action Units (AUs) detection, while graded changes in their intensity have rarely been...     

Alginate/gelatin crosslinked system through Maillard reaction: preparation,characterization and biological properties

Maillard reaction (MR) was studied in aqueous model systems containing gelatin and sodium alginate, which were heat treated for different pH (7, 8, 9, 10 and 11) at three temperatures (70, 80 and 90 °C). Some indicators were used to evaluate this reaction:degree of crosslinking, release of gelatin, free amino groups and browning intensities. The results indicated that alginate/gelatin crosslinked by MR showed an increase of degree of crosslinking as the pH and temperatures were increasing while release of gelatin decreased. Furthermore, samples prepared at a high temperature exhibited stronger browning intensity owing to the formation of Maillard reaction products (MRPs). The obtained materials were analyzed by FTIR and XRD. The antioxidant ability by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and power reducing, as well as the anti-inflammatory activity were investigated.     

Synthesis and properties of novel hydrogels from oxidized pectin crosslinked gelatin for biomedical applications

Gelatin (G) edible films with a new kind of dialdehyde polysaccharide, oxidized pectin (OP) as crosslinking agent are successfully prepared using casting techniques. FTIR and X-ray diffraction studies demonstrate that crosslinking is achieved through the reaction of aldehyde groups of oxidized pectin with the free amino groups in gelatin with a small affectation of the triple helix of gelatin. The qualitative and quantitative data about structures of films were determined by atomic force microscopy. Thermogravimetric analysis reveals that G/OP film has improved thermal stability in comparison with pure gelatin. Examination of the hemolytic potential showed that the obtained hydrogels are non-hemolytic in nature. These hydrogels are also nontoxic and blood-compatible. This kind of hydrogel is expected to be useful in the biomedical field, e.g., as wound dressing.     

Poly(4-vinylpyridine isopentyl bromide) as inhibitor for corrosion of pure iron in molar sulphuric acid

The effect of poly(4-vinylpyridine isopentyl bromide) (P4VPIPBr) in three degrees of quaternisation (6, 18 and 79%) on the corrosion of pure iron in molar sulphuric acid is investigated by potentiodynamic, polarisation resistance and weight loss measurements. The inhibition efficiency (E%) of P4VPIPBr increases with its concentration to attain 100% around 5×10⁻⁶ M. E% values obtained from the various methods are in good agreement. Polarisation measurements show also that the compound acts as a cathodic inhibitor and adsorbs on the pure iron surface according to the Frumkin adsorption isotherm model.     

Investigation on LP-residual representations for speaker identification

Feature extraction is an essential and important step for speaker recognition systems. In this paper, we propose to improve these systems by exploiting both conventional features such as mel frequency cepstral coding (MFCC), linear predictive cepstral coding (LPCC) and non-conventional ones. The method exploits information present in the linear predictive (LP) residual signal. The features extracted from the LP-residue are then combined to the MFCC or the LPCC. We investigate two approaches termed as temporal and frequential representations. The first one consists of an auto-regressive (AR) modelling of the signal followed by a cepstral transformation in a similar way to the LPC-LPCC transformation. In order to take into account the non-linear nature of the speech signals we used two estimation methods based on second and third-order statistics. They are, respectively, termed as R-SOS-LPCC (residual plus second-order statistic based estimation of the AR model plus cepstral transformation) and R-HOS-LPCC (higher order). Concerning the frequential approach, we exploit a filter bank method called the power difference of spectra in sub-band (PDSS) which measures the spectral flatness over the sub-bands. The resulting features are named R-PDSS. The analysis of these proposed schemes are done over a speaker identification problem with two different databases. The first one is the Gaudi database and contains 49 speakers. The main interest lies in the controlled acquisition conditions: mismatch between the microphones and the interval sessions. The second database is the well-known NTIMIT corpus with 630 speakers. The performances of the features are confirmed over this larger corpus. In addition, we propose to compare traditional features and residual ones by the fusion of recognizers (feature extractor + classifier). The results show that residual features carry speaker-dependent features and the combination with the LPCC or the MFCC shows global improvements in terms of robustness under different mismatches. A comparison between the residual features under the opinion fusion framework gives us useful information about the potential of both temporal and frequential representations.     

Poly(4-vinylpyridine-poly(3-oxide-ethylene) tosyle) as an inhibitor for iron in sulphuric acid at 80 °C

The influence of poly(4-vinylpyridine-poly(3-oxide-ethylene) tosyle) P4VPPEO5000Ts, on the corrosion inhibition of iron in molar sulphuric acid solution is studied using weight-loss, polarisation resistance, potentiodynamic and EIS measurements. P4VPPEO5000Ts is an excellent inhibitor and its inhibition efficiency increases with the increase of concentration to attain 100% since 2.5 × 10⁻⁸ M. Potentiodynamic polarisation studies clearly reveal that it acts as a mixed-type inhibitor. The polymer studied reduces the corrosion rates. E% values obtained from weight-loss, corrosion current density, polarisation resistance and EIS methods are in good agreement. Adsorption of this compound on iron surface has an S-shaped adsorption isotherm with two consecutive steps.