Efficiency and optimisation of fin with temperature-dependent thermal conductivity: a simplified solution

An analytical simplified solution is proposed for temperature distribution and fin efficiency, when thermal conductivity is temperature dependent. An optimal linearization technique is used to solve the nonlinear equation. Based on classical solution, some accurate results are obtained and presented with thermal conductivity parameter and fin parameter. Arithmetic mean temperature is less precise than an equivalent thermal conductivity. Optimal thickness for rectangular fin is derived.     

Adsorption of hydrogen in defective carbon nanotube: modelling and consequent investigations using statistical physics formalism

ABSTRACT

Experimental adsorption isotherms of hydrogen in CNT samples (CNT-A, activated CNT-A CNT-B and activated CNT-B) at T?=?77, 87 and 90?K have been fitted using some theoretical model expressions treated by statistical physics through the grand canonical ensemble. The monolayer model with single energy is selected to fit and interpret the experimental data obtained with CNTs. The physico-chemical parameters, interfering in the adsorption process and implicated in the model expressions, could be directly determined from the experimental data through numerical simulation. Three parameters of the model are fitted, namely the number of hydrogen molecule per site n, the interstitial site density N_m and the energetic parameter P_1/2. The evolution of these parameters as function of temperature is plotted and interpreted in relation to adsorption process. Finally, the thermo-dynamic potential functions, which involve in the adsorption mechanism like free enthalpy of Gibbs G_a, internal energy E_int and entropy S_a, are derived by statistical physics calculations from the selected model.     

Synthesis and Diels-Alder reactivity of ortho-carbazolequinones

Oxidation of 2- and 3-hydroxycarbazoles with Frémy's salt gave the corresponding ortho-carbazolequinones. These molecules react as carbodienophiles in Diels-Alder reaction with 1-acetoxy-1,3-butadiene and 1,3-cyclopentadiene to provide the novel benzocarbazolequinone structures 15, 16, 18 and 19.     

Equations différentielles invariantes sur les groupes et algèbres de Lie réductifs II

Dans un article précédent, nous avons démontré que si D est un opérateur différentiel bi-invariant sur un groupe réductif G vérifiant la condition de Benabdallah-Rouvière, alors on peut résoudre l’équation différentielle Du=v dans l'espace des distributions G-invariantes (par automorphismes intérieurs) d'ordre fini; nous allons montrer ici que, sous la même hypothèse, on peut résoudre cette équation dans l'espace de toutes les distributions G-invariantes. D'autre part, nous donnons un exemple dans qui montre que les équations différentielles invariantes dans les algèbres de Lie réductives ne sont pas toujours résolubles dans l'espace des fonctions indéfiniment différentiables invariantes.     

Synthesis of high added value compounds through catalytic oxidation of 2-phenylethanol: A Kinetic study

An effective procedure was developed to produce high-value added phenolic compounds through the conversion of 2-phenylethanol (2-PhEt) by using acid-activated clays KSF for the hydrogen peroxide. Owing to KSF's ability to catalyze a variety of complex oxidations, it was likely to convert 2-PhEt to hydroxytyrosol (HTY) and tyrosol (TY) derivatives. The analyses of catalytic solution revealed that the optimum conditions, giving a higher concentration of oxidation products such as HTY, were as follows: 2-PhEt concentration 10⁻² mol/L, the hydrogen peroxide concentration 5.05 × 10⁻² and 0.6 g L^–1 of KSF clays . The yield during the conversion reaction into HTY was around 25%. All compounds in the reaction mixture were identified by mass spectrophotometry using a LC-MS apparatus. HTY, TY, meta-tyrosol and ortho-tyrosol were the major compounds. The antioxidant activity was realized by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. In fact, it is revealed that the strongest inhibition percentage (PI = 96) was detected with the increase in the concentration of HTY. The approach proposed in the present work presents an environment friendly method.     

Réactivité de l’acide déhydroacétique hydrogené en c5-c6 : obtention des pyrano-1,5-benzodiazépines différemment substituées et de la structure enaminone

A number of 1,5-benzodiazepines derivatives 4 were obtained via the interaction of dehydroacetic acid hydrogenated at C₅-C₆, orthophenylenediamines and aromatic aldehydes. The interpretation of the results is enriched by a study of the electronic effects of the DHA hydrogenated at C₅-C₆. Accordingly, it leads us to obtain the original structure cynnamoyle 5.     

Targeting the proangiogenic VEGF-VEGFR protein-protein interface with drug-like compounds by in silico and in vitro screening

Protein-protein interactions play a central role in medicine, and their modulation with small organic compounds remains an enormous challenge. Because it has been noted that the macromolecular complexes modulated to date have a relatively pronounced binding cavity at the interface, we decided to perform screening experiments over the vascular endothelial growth factor receptor (VEGFR), a validated target for antiangiogenic treatments with a very flat interface. We focused the study on the VEGFR-1 D2 domain, and 20 active compounds were identified. These small compounds contained a (3-carboxy-2-ureido)thiophen unit and had IC₅₀ values in the low micromolar range. The most potent compound inhibited the VEGF-induced VEGFR-1 transduction pathways. Our findings suggest that our best hit may be a promising scaffold to probe this macromolecular complex and for the development of treatments of VEGFR-1-dependent diseases.     

Chemical composition and biological potential of seed oil and leaf extracts of Henophyton deserti Coss. & Durieu

Henophyton deserti was characterized in respect to its chemical composition, antioxidant potential and antimicrobial activity. Fourteen compounds were identified by LC/MS, GC/MS, and GC in leaf and seed extracts. Total flavonoids ranged between 45.66 and 181.2 mg QE g^?1 and 2.03 and 38.95 mg QE g^?1 dry weight (dw) in leaf and seed polar extracts, respectively. Rutin, Kaempferol 3-rutinoside, Diosmetin 7-O-Glucoside, and Acacetin 7-O-Glucoside flavonoids were tentatively identified in this plant. The profile of seed fatty acids revealed oleic acid (C18:1, 27%), linoleic acid (C18:2, 12%) and linolenic acid (C18:3, 17%). The highest antioxidant activities of 85.2% and 67.5% were obtained with methanol and ethyl acetate leaf extracts. All H. deserti extracts were active against at least one of the tested bacteria, leaf ethyl acetate extract showed the lowest MIC of 0.156 mg ml^?1. Only seed ethyl acetate extract showed antifungal activity with a MIC of 2.5 mg ml^?1.