activation parameters
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V. R. Adinarayanan ◽  
P. Preethi Kumari ◽  
Suma A. Rao

AbstractSynthesis and inhibition effectiveness of (2E)-2-(furan-2-ylmethylidene) hydrazine carbothioamide (FMHC) as an inhibitor for corrosion of mild steel in 0.5 M H2SO4 is reported. Experiments were conducted at various temperatures (303–323 K) by adopting potentiodynamic polarization and electrochemical impedance spectroscopy. Readings obtained demonstrated that percentage inhibition efficiency (% IE) improved with the upsurge in the concentration of FMHC, while it decreased with a rise in temperature. The highest % IE observed was 60% for 2.5 × 10–4 M FMHC at 303 K. FMHC worked moderately as a mixed inhibitor. FMHC obeyed the Langmuir model of adsorption and the mode of adsorption was physisorption on the mild steel surface which was further endorsed by examining the surface using the scanning electron microscope. A clear insight into the mechanistic features of corrosion inhibition by using FMHC was acquired. Calculation of activation parameters helped to suggest an appropriate mechanism for the adsorption of FMHC on mild steel through quantum chemical calculations using density functional theory (DFT). Graphical abstract

В.О. Попов ◽  
В.Н. Комов ◽  
Е.М. Попенко ◽  
А.В. Сергиенко

Определены формально-кинетические характеристики термораспада нитро-нитрозоаминов и их смесей с октогеном. Реакция разложения нитрозоаналогов октогена и нитро-нитрозопроизводных тетраазадекалина характеризуется меньшей энергией активации по сравнению с октогеном, и протекает с большей скоростью. Проведен анализ активационных параметров термораспада смесей, установлено активирующее влияние нитрозопроизводных тетраазадекалина на разложение октогена. The formal-kinetic characteristics of the thermal decomposition of nitro-nitrosoamines and their mixtures with HMX have been determined. The decomposition reaction of nitroso analogs of HMX and nitro-nitroso derivatives of tetraazadecalin is characterized by a lower activation energy compared to HMX, and proceeds at a higher rate. The analysis of the activation parameters of the thermal decomposition of the mixtures was carried out, the activating effect of the nitroso derivatives of tetraazadecalin on the decomposition of HMX was established.

Platelets ◽  
2021 ◽  
pp. 1-8
Fanny Vardon-Bounes ◽  
Cédric Garcia ◽  
Alexandra Piton ◽  
Jennifer Series ◽  
Marie-Pierre Gratacap ◽  

2021 ◽  
pp. 26-29
N.P. Dikiy ◽  
Yu.V. Lyashko ◽  
E.P. Medvedeva ◽  
D.V. Medvedev

The comparison of the catalytic activity of the initial and activated by bremsstrahlung -radiation on a high-current electron accelerator of zirconium dioxide nanoparticles on the nature of the conversion of ethanol. The used -activation parameters contributed to the formation of a more perfect crystal structure of ZrO2 nanoparticles. It was shown that when using -activated ZrO2 nanoparticles as a catalyst, the yield of hydrocarbon products during the conversion of ethanol was several times higher than the yield of the same products in the case of using the initial ZrO2 nanoparticles. The mechanism of such a conversion of ethanol can be associated with the synergism of large ionization losses of Auger electrons and the effect of highly reactive products involved in heterogeneous catalysis.

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7155
Bjarte Aarmo Lund ◽  
Bjørn Olav Brandsdal

The determination of the temperature dependence of enzyme catalysis has traditionally been a labourious undertaking. We have developed a new approach to the classical Arrhenius parameter estimation by fitting the change in velocity under a gradual change in temperature. The evaluation with a simulated dataset shows that the approach is valid. The approach is demonstrated as a useful tool by characterizing the Bacillus pumilus LipA enzyme. Our results for the lipase show that the enzyme is psychrotolerant, with an activation energy of 15.3 kcal/mol for the chromogenic substrate para-nitrophenyl butyrate. Our results demonstrate that this can produce equivalent curves to the traditional approach while requiring significantly less sample, labour and time. Our method is further validated by characterizing three α-amylases from different species and habitats. The experiments with the α-amylases show that the approach works over a wide range of temperatures and clearly differentiates between psychrophilic, mesophilic and thermophilic enzymes. The methodology is released as an open-source implementation in Python, available online or used locally. This method of determining the activation parameters can make studies of the temperature dependence of enzyme catalysis more widely adapted to understand how enzymes have evolved to function in extreme environments. Moreover, the thermodynamic parameters that are estimated serve as functional validations of the empirical valence bond calculations of enzyme catalysis.

Viruses ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2376
Silke Huber ◽  
Mariam Massri ◽  
Marco Grasse ◽  
Verena Fleischer ◽  
Sára Kellnerová ◽  

Overactivation of the complement system has been characterized in severe COVID-19 cases. Complement components are known to trigger NETosis via the coagulation cascade and have also been reported in human tracheobronchial epithelial cells. In this longitudinal study, we investigated systemic and local complement activation and NETosis in COVID-19 patients that underwent mechanical ventilation. Results confirmed significantly higher baseline levels of serum C5a (24.5 ± 39.0 ng/mL) and TCC (11.03 ± 8.52 µg/mL) in patients compared to healthy controls (p < 0.01 and p < 0.0001, respectively). Furthermore, systemic NETosis was significantly augmented in patients (5.87 (±3.71) × 106 neutrophils/mL) compared to healthy controls (0.82 (±0.74) × 106 neutrophils/mL) (p < 0.0001). In tracheal fluid, baseline TCC levels but not C5a and NETosis, were significantly higher in patients. Kinetic studies of systemic complement activation revealed markedly higher levels of TCC and CRP in nonsurvivors compared to survivors. In contrast, kinetic studies showed decreased local NETosis in tracheal fluid but comparable local complement activation in nonsurvivors compared to survivors. Systemic TCC and NETosis were significantly correlated with inflammation and coagulation markers. We propose that a ratio comprising systemic inflammation, complement activation, and chest X-ray score could be rendered as a predictive parameter of patient outcome in severe SARS-CoV-2 infections.

A.K. Singh

The kinetic result of hydrolysis of Ethyl Caprlyate has been investigated at different composition of aqueous-organic solvent with Acetone (30-70% v/v) over the temperature range of 20 to 400c. The calculated result follows second order kinetics and is observed that the rate decreases with increasing proportion of Acetone. This behavior is attributed electrostatic nature that various solvent-solute interaction in reaction media. Linear plots of Logk against water concentration shows that equilibrium shifted from dense form to bulky form. Iso-kinetic temperature has been determined with the help of slopes of (ΔH*) versus (ΔS*). Thermodynamic parameter has been calculated with the help of Wynne-Jones and Eyring equation.

Hosein Ghaedi ◽  
Payam Kalhor ◽  
Ming Zhao ◽  
Peter T. Clough ◽  
Edward J. Anthony ◽  

AbstractIs it possible to improve CO2 solubility in potassium carbonate (K2CO3)-based transition temperature mixtures (TTMs)? To assess this possibility, a ternary transition-temperature mixture (TTTM) was prepared by using a hindered amine, 2-amino-2-methyl-1,3-propanediol (AMPD). Fourier transform infrared spectroscopy (FT-IR) was employed to detect the functional groups including hydroxyl, amine, carbonate ion, and aliphatic functional groups in the prepared solvents. From thermogravimetric analysis (TGA), it was found that the addition of AMPD to the binary mixture can increase the thermal stability of TTTM. The viscosity findings showed that TTTM has a higher viscosity than TTM while their difference was decreased by increasing temperature. In addition, Eyring’s absolute rate theory was used to compute the activation parameters (∆G*, ∆H*, and ∆S*). The CO2 solubility in liquids was measured at a temperature of 303.15 K and pressures up to 1.8 MPa. The results disclosed that the CO2 solubility of TTTM was improved by the addition of AMPD. At the pressure of about 1.8 MPa, the CO2 mole fractions of TTM and TTTM were 0.1697 and 0.2022, respectively. To confirm the experimental data, density functional theory (DFT) was employed. From the DFT analysis, it was found that the TTTM + CO2 system has higher interaction energy (|∆E|) than the TTM + CO2 system indicating the higher CO2 affinity of the former system. This study might help scientists to better understand and to improve CO2 solubility in these types of solvents by choosing a suitable amine as HBD and finding the best combination of HBA and HBD.

Ajay Rathore ◽  
Vijay Devra

The goal of the research was to devise a simple and environment-friendly approach to synthesize iron nanoparticles (FeNPs) and evaluate the catalytic activity of biosynthesized FeNPs for the degradation of the cationic dye Malachite Green (MG) in the presence of Peroxomonosulphate (PMS). Different instrumental approaches were used to characterize green produced FeNPs, and the results show that the NPs are spherical and 48 nm in size. Increasing the concentrations of nanoparticles (0.5 × 10-8 - 2.0 × 10-8 mol/dm3), Peroxomonosulphate (1.0 × 10-4 - 5.0 × 10-4 mol/dm3), dye (1.0 × 10-5 - 5.0 × 10-5 mol/dm3), pH (5), and high temperature (25-35 °C) enhanced the degradation kinetics of Pseudo-first-order kinetics were used to describe the degradation of MG in the FeNPs/PMS system, and activation parameters were derived. The maximum MG degrading efficiency for the FeNPs/PMS system was 88% in 60 minutes under optimum reaction conditions. The structure of intermediates formed by MG degradation by FeNPs/PMS was determined using UV-vis spectrum analysis. The application of synthesized FeNPs to improve Peroxomonosulphate oxidation potential for MG degradation is a unique, efficient, promising, and eco-friendly technology because it does not require any expensive reagents.  

2021 ◽  
pp. 174751982110459
Monirul Islam ◽  
Swarnava Singha ◽  
Anwesha Bhattacharyya ◽  
Debraj Roy

Chromic acid oxidation of d,l-mandelic acid in the presence and absence of 1,10-phenanthroline (Phen) is studied in an aqueous micellar medium under kinetic conditions, [d,l-mandelic acid] >> [Phen]T >> [Cr(VI)]T at different temperatures. From studies on the effect of temperature on the rate constant (k), the activation parameters ∆H≠ (enthalpy of activation) and ∆S≠ (entropy of activation) are evaluated by using the Eyring equation [−ln (kh/kBT) = ∆H≠/RT − ∆S≠/R]. The high value of ∆H≠ indicates that the phen-catalysed path is favoured mainly due to very high negative value of ∆S≠. The negative value of ∆S≠ and the composite rate constant kcat support the suggested cyclic transition state. Both the catalysed and uncatalysed paths show a first-order dependence on [H+], and both also show a first-order dependence on [d,l-mandelic acid]T and [Cr(VI)]T. The Phen-catalysed path is first order in [Phen]T. These observations remain unaltered in the presence of externally added surfactants. The cationic surfactant N-cetylpyridinium chloride is found to retard the rate of the reaction.

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