Reaction kinetics of cinnamaldehyde hydrogenation over Pt/SiO2: comparison between bulk and intraparticle diffusion models

The liquid-phase hydrogenation of cinnamaldehyde over a Pt/SiO2 catalyst was investigated experimentally and theoretically. The experiments were conducted in a 300 cm3 stainless steel stirred batch reactor supplied with hydrogen gas and ethanol as a solvent. Five Langmuir–Hinshelwood kinetic models were investigated to fit the experimental data. The predictions from the bulk model were compared with predictions from the intraparticle diffusion model. Competitive and non-competitive mechanisms were applied to produce the main intermediate compound, cinnamyl alcohol. Reaction rate parameters for the different reaction steps were calculated by comparing between the experimental and mathematical models. All rate data utilized in the present study were obtained in the kinetic regime. The kinetic parameters were obtained by applying a nonlinear dynamic optimization algorithm. Nevertheless, the comparison between the methodology of the present model and these five models indicated that the non-competitive mechanism is more acceptable and identical with the single-site Langmuir–Hinshelwood kinetic model including mass transfer effects and it mimicked the reactant behavior better than the other models. In addition, the observed mean absolute error (MAE) for the non-competitive mechanism of the present model was 2.3022 mol/m3; however, the MAE for the competitive mechanism was 2.8233 mol/m3, which is an increase of approximately 18%. The prediction of the intraparticle diffusion model was found to be very close to that of the bulk model owing to the use of a catalyst with a very small particle size (<40 microns). Employing a commercial 5% Pt/SiO2 catalyst showed a result consistent with previous research using different catalysts, with an activation energy of ≈24 kJ/mol

A fatal case of probable neurobehcet

Behçet's disease (BD) is a systemic vasculitis characterized by recurrent oral and genital ulcers, with a frequent ocular and skin involvement. Neurological involvement in BD has been reported in 4–49% of cases and determines functional and vital prognosis of the disease. Based on clinical and imaging evidence, two major forms can be identified: a parenchymal or an extra parenchymal involvement essentially represented by cerebral vein thrombosis. Awareness disorders are rarely reported as tell-tale signs of neurological involvement in BD. We hereby report the peculiar case of a young patient, 39 years old, admitted to the emergency department for an acute onset of altered mental status in a non-traumatic setting where investigations led to the diagnosis of neurobehçet disease. Patient was placed on high doses corticosteroids with unfavorable outcome; patient passed away after 01 week

Pharmacognostic and Antioxidant activity of Bryophyllum pinnatum Leaves

Bryophyllum pinnatum is used in ethno medicine for treatment of earache, burns, abscesses, ulcer, insect bites, and diarrhoea. In Nigeria, this herb is used to facilitate the dropping of the placenta of a newly born baby. To search for new sources of safe and inexpensive antioxidants, the leaf of Bryophyllum pinnatum was screened for its antioxidant activity. Sample of leaf from B. pinnatum was tested for organoleptic, phytochemical, thin layer chromatography and antioxidant activity using standard procedure. The leaf was found to be simple, petiolated 6.8cm in size. Microscopically, the leaf had irregularly shaped epidermal cells with numerous anisocytic stomata on the lower surface. Chemomicroscopical evaluation revealed the presence of cellulose, tannins, starch, lignin, calcium oxalate, suberin, aleurone grain and mucilage with the exception of calcium carbonate. Phytochemicals which include alkaloids, phenols, flavonoids, saponins, tannins, carbohydrates and triterpenes were detected in both aqueous and methanolic extracts while anthraquinones was absent. Methanol extract when developed in Chloroform: Methanol (9:1) and virtualized with p-Anisaldehyde/H2SO4, it gave six spots. The DPPH radical scavenging ability of the extract showed the following trend Ascorbic acid &gt; extract. These results suggested that B. pinnatum leaves have moderate antioxidant potentials. Further study is necessary for isolation and characterization of active antioxidant agents which can be used to treat various oxidative stress related diseases