Influence of Differential Diffusion on Super-Equilibrium Temperature in Turbulent Non-Premixed Hydrogen/Air Flames

In this paper we wish to investigate the occurrence of super-equilibrium temperature values, observed in many experimental configurations. We would like to understand the origin of this phenomenon. Previous authors have already shown that differential diffusion can lead to considerable changes in the temperature field and we would like to build on top of this observation. We investigate numerically super-equilibrium combustion by considering both laminar counter-flow and turbulent diluted hydrogen/air diffusion flames. These turbulent flames are computed using direct numerical simulations (DNS). A detailed reaction mechanism is employed and the transport properties are modeled using multicomponent diffusion velocities, including the Soret effect. Analyzing these results we introduce three complementary parameters (dilution-free mixture fraction, dilution excess and local enthalpy) to describe the local combustion conditions. Introducing a measure of dilution separately from the mixture fraction is necessary for a proper analysis. Using this set of parameters it becomes possible to explain super-equilibrium temperature levels as a consequence of differential diffusion.     

Herbal Arsenal against Skin Ailments: A Review Supported by In Silico Molecular Docking Studies

Maintaining healthy skin is important for a healthy body. At present, skin diseases are numerous, representing a major health problem affecting all ages from neonates to the elderly worldwide. Many people may develop diseases that affect the skin, including cancer, herpes, and cellulitis. Long-term conventional treatment creates complicated disorders in vital organs of the body. It also imposes socioeconomic burdens on patients. Natural treatment is cheap and claimed to be safe. The use of plants is as old as mankind. Many medicinal plants and their parts are frequently used to treat these diseases, and they are also suitable raw materials for the production of new synthetic agents. A review of some plant families, viz., Fabaceae, Asteraceae, Lamiaceae, etc., used in the treatment of skin diseases is provided with their most common compounds and in silico studies that summarize the recent data that have been collected in this area.     

Iron Oxide Nanoparticle-Based Ferro-Nanofluids for Advanced Technological Applications

Iron oxide nanoparticle (ION)-based ferro-nanofluids (FNs) have been used for different technological applications owing to their excellent magneto-rheological properties. A comprehensive overview of the current advancement of FNs based on IONs for various engineering applications is unquestionably necessary. Hence, in this review article, various important advanced technological applications of ION-based FNs concerning different engineering fields are critically summarized. The chemical engineering applications are mainly focused on mass transfer processes. Similarly, the electrical and electronics engineering applications are mainly focused on magnetic field sensors, FN-based temperature sensors and tilt sensors, microelectromechanical systems (MEMS) and on-chip components, actuators, and cooling for electronic devices and photovoltaic thermal systems. On the other hand, environmental engineering applications encompass water and air purification. Moreover, mechanical engineering or magneto-rheological applications include dampers and sealings. This review article provides up-to-date information related to the technological advancements and emerging trends in ION-based FN research concerning various engineering fields, as well as discusses the challenges and future perspectives.     

Spectroscopic characterization of some metal complexes derived from 4-acetylpyridine nicotinoylhydrazone

Coordination compounds of Mn^II, Cu^II, Fe^III and Zn^II ions with 4-acetylpyridine nicotinoylhydrazone (4-APNH) were synthesized and characterized by elemental analyses, molar conductivity, magnetic moments, i.r., u.v./vis., m.s., ¹H-n.m.r. and thermal analyses. I.r. spectra show that the ligand can act either in the enol form as monovalent bidentate or in the keto form as neutral bidentate depending on the metal salt used. Octahedral structures are proposed for Fe complex and square – planar for the Cu complex, while tetrahedral structures were suggested for Zn and Mn complexes on the basis of magnetic and spectral evidences. Semi-empirical calculations ZINDO/1 have been used to study the molecular geometry and the harmonic vibrational spectra with the purpose to assist the experimental assignment of the complexes. In memory of the late Professor Dr. Abdel Hamid M. Shallaby 2/5/2006     

Demulsification Efficiency of Some New Demulsifiers Based on 1,3,5-Triethanolhexahydro-1,3,5-triazine

This study mainly concentrates on the synthesis of three novel demulsifiers and the investigation of their demulsification efficiency. The demulsifiers were derived from 1,3,5-triethanolhexahydro-1,3,5-triazine, which was prepared by the reaction of monoethanol amine with formaldehyde. The 1,3,5-triethanolhexahydro-1,3,5-triazine was ethoxylated by introducing 20 units of ethylene oxide and then esterified at different molar ratios with oleic acid (1, 2, and 3) to give three demulsifiers, namely, E₂₀TO, E₂₀TO₂, and E₂₀TO₃. The chemical structures of the prepared demulsifiers were confirmed by ¹H NMR and FTIR spectrum. The demulsification efficiency of these demulsifiers was tested on the natural water-in-oil (w/o) emulsions (50% water content). From the obtained results, it has been found that the investigated demulsifiers have a great potential to break the w/o emulsions. The trioleat ester (E₂₀TO₃) exhibited the maximum demulsification efficiency (96%) after 120 minutes at 55°C.     

Conformation of acetate derivatives of sugars and other cyclic alcohols. Crystal structures, NMR studies, and molecular mechanics calculations of acetates. When is the exocyclic C-O bond eclipsed?

[reaction: see text] A study of published crystal structures (of O-acetylated sugars for the most part) suggests that the exocyclic C-O bond in acetate esters of cyclic alcohols intrinsically prefers a staggered conformation, although the eclipsed conformation is only slightly less stable. When the acetate is flanked by two equatorial substituents the preferred conformation is close to eclipsed. Over 1500 C-OAc bonds have been analyzed. Diagnostic NMR criteria for torsion angles and MM3 calculations are reported and confirm these conclusions.     

conversion of trimethylsilyl ethers to acetyl or formyl esters with TiCl4

A simple method is described for the efficient conversion of trimethylsilyl ethers to their corresponding acetyl and formyl esters in refluxing ethyl acetate or ethyl formate in the presence of TiCl₄.     

Non‐linear absorption of an intense laser pulse propagating in wiggler‐assisted underdense collisional plasma

In this article, the propagation of an intense laser pulse through underdense collisional plasma in the presence of planar magnetostatic wiggler is studied. It is shown that the electron density distribution, in the presence of planar wiggler with increasing of the normalized plasma length, increases initially and then reaches a peak for different values of wiggler amplitudes. In addition, it is found that the existence of wiggler field leads to an increase in the electron density distribution and subsequently enhancement of electric field. Moreover, it is observed that by increasing the wiggler field, as a result of the increase of the electron density distribution, the dielectric permittivity constant is reduced. It is seen that while wiggler magnetic field was applied appropriately, the total absorption coefficient in the underdense collisional isothermal magnetized plasma improves. In fact, increase of wiggler magnetic field causes the enhancement of the total absorption coefficient of plasma medium.