Synthesis and characterization of poly(p‐phenylene)‐graft‐poly(ε‐caprolactone) copolymers by combined ring‐opening polymerization and cross‐coupling processes

2,5‐Dibromo‐1,4‐(dihydroxymethyl)benzene was used as initiator in ring‐opening polymerization of ε‐caprolactone in the presence of stannous octoate (Sn(Oct)₂) catalyst. The resulting poly(ε‐caprolactone) (PCL) macromonomer, with a central 2,5‐dibromo‐1,4‐diphenylene group, was used in combination with 1,4‐dibromo‐2,5‐dimethylbenzene for a Suzuki coupling in the presence of Pd(PPh₃)₄ as catalyst or using the system NiCl₂/bpy/PPh₃/Zn for a Yamamoto‐type polymerization. The poly(p‐phenylenes) (PPP) obtained, with PCL side chains, have solubility properties similar to those of the starting macromonomer, ie soluble in common organic solvents at room temperature. The new polymers were characterized by ¹H and ¹³C NMR and UV spectroscopy and also by GPC measurements. The thermal behaviour of the precursor PCL macromonomer and the final poly(p‐phenylene)‐graft‐poly(ε‐caprolactone) copolymers were investigated by thermogravimetric analysis and differential scanning calorimetry analyses and compared. Copyright © 2004 Society of Chemical Industry     

A spin wave resonance study on reentrant Au77Fe23 films

Thin films prepared by both flash and slow evaporation of the bulk Au₇₇Fe₂₃ alloy have been studied by electron spin resonance (ESR) technique at the temperature range between 77–300 K. A series of spin wave resonance (SWR) peaks were observed at all temperatures when the external de magnetic field is applied along the directions lying in a small angular interval with respect to the film normal. The classical spin wave model has been used to analyze the experimental data. The magnetic parameters, such as exchange stiffness constant, the effective bulk and the surface anisotropy energy parameters of the system have been derived as a function of temperature. While the easy plane surface anisotropy almost remains constant, considerable increments were found in the exchange parameter, the magnetization and the linewidth with decreasing temperature. The SWR linewidths for the films obtained by slow evaporation at higher substrate temperatures are noticeably smaller compared to those of the film prepared by flash evaporation technique.     

Experimental testing of a new solar dryer

Drying of agricultural products is an energy-intensive operation. High prices and shortages in fossil fuels increase the emphasis on using solar energy as an alternative energy source, especially in developing countries. In this respect, a new solar dryer, which consisted of a solar air heater and a drying chamber, was developed and used for drying various fruits and vegetables, i.e., sultana grapes, green beans, sweet peppers and chilli peppers and was successfully tested. In order to make a comparison, the traditional sun-drying experiments were employed. Results showed that the solar dryer reduced the drying time significantly and prevented mass losses, and essentially provided better product quality.     

New application of the fixed bed reactor to the measurement of coal reactivity under dynamic combustion conductions

A new laboratory scale facility (fixed bed reactor) for the determination of solid fuel reactivity is presented. The reactivity is measured by burning samples of partially pyrolysed coals under dynamic conditions (rapid change of temperature and oxygen concentration). Mass conversion rate is determined from heat and mass balance equations, and the influence of boundary layer diffusion and chemical reaction rate on the measured reaction rate is evaluated. In the scope of a co-operative test, the reactivity of Göttelborn bituminous coal has been investigated by different research institutions. Despite of the different conditions in different laboratory scale facilities, a good correspondence of results was found. Moreover, three coals of different rank have been investigated. The kinetic constants of these coals are also given.     

Combined ℋ︁∞/LQG control via the optimal projection equations: On minimizing the LQG cost bound

The Optimal Projection equations for combined ??_∞/LQG control are considered. Positive semidefiniteness of the associated Lagrange multiplier is shown to be necessary for the LQG cost bound to be minimal. It follows that all four Optimal Projection equations have a role to play, even in the full-order case.     

Role of pretreatment with potassium permanganate and urea on mechanical and degradable properties of photocured coir (Cocos nucifera) fiber with 1,6‐hexanediol diacrylate

Coir fibers were modified with 1,6‐hexanediol diacrylate (HDDA) using ultraviolet (UV) radiation. Concentration of HDDA, soaking time, and radiation dose were optimized and found to be 30% HDDA in methanol along with photoinitiator Irgacure‐500 (2%) and 120 min of soaking time registered as the better performance (polymer loading (PL) 7%, tensile strength factor, T_f = 1.50). Urea of different concentrations (0.5–2%) were incorporated with 30% HDDA to monitor its effect on the properties and 1% urea produced the best results (PL = 25%, T_f = 1.82). For the improvement of the properties, the fibers were subjected to surface treatment with potassium permanganate (KMnO₄) of different concentrations at various treating times. Enhanced properties (PL = 86%. T_f = 4.42) of the fibers treated with KMnO₄ (0.05%) were obtained. The KMnO₄ treated fibers were again treated with HDDA (30%) solution along with urea (1%) and found to produce the best results (PL = 100%, T_f = 4.5). Water uptake and degradable properties of the treated and virgin fibers were obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4361–4368, 2006     

Anaerobic/aerobic sequential treatment of a cotton textile mill wastewater

The treatment of a wastewater taken from a cotton textile mill was investigated using an anaerobic/aerobic sequential system during an operational period of 87 days. The process units consisted of an upflow anaerobic sludge blanket (UASB) reactor and a continuous stirred tank reactor (CSTR). Wastewater characterization was performed before feeding the reactor system. Glucose‐COD, and azo dyes were added to the textile wastewater for comparative purposes in the final period of operation. The pH values in the effluent of the UASB reactor were suitable for optimal anaerobic treatment in all runs. The biodegradable part of the COD in wastewater was removed effectively, with the anaerobic stage improving the biodegradability of wastewater entering the aerobic stage. The UASB reactor permitted COD and color removals of 9–51% and 46–55%, respectively, at a hydraulic retention time (HRT) of 30 h. COD removal efficiencies were between 40 and 85% and color removal efficiencies were 39–81% in normal and artificially‐colored wastewaters at a total HRT of 5.75 days in the UASB/CSTR reactor system. Benzidine produced from the cleavage of azo bond in the anaerobic stage was effectively removed in the aerobic stage, and was identified by comparison of its HPLC spectrum with that of an authentic specimen. Copyright © 2004 Society of Chemical Industry     

Bisoxathiolane sulfides from a dioxoene fatty acid

A quantitative preparation of bisoxathiolane from 9,12-dioxo-trans-10-octadecenoic acid is discussed. The reagents used are β-mercaptoethanol and BF₃₋ etherate in acetic acid. The structure of the product was established with the help of elemental analysis, infrared, nuclear magnetic resonance and mass spectroscopy data.     

A Fuzzy Petri Net for Pattern Recognition: Application to Dynamic Classes

When involving evolutionary natural objects, the odeling of dynamic lasses is the main issue for a pattern recognition system. This problem an be avoided by making dynamic the syste of pattern recognition which an then enter into various states according to the evolution of the lasses. We propose a dynamic recognition system founded on two types of learning. The static aspect of the learning is ensured by lassifiers or systems of lassifiers, while the dynamic aspect is translated by the learning of the planning of the various states by a fuzzy Petri net. The method is sucessfully applied to a synthetic data set. Received 21 September 2000 / Revised 19 December 2000 / Accepted in revised form 1 March 2001     

Investigation on the Neutronic Performance of a Fusion Reactor Using Flibe with Heavy Metal Fluorides

Using liquid wall between the plasma and solid first wall in a fusion reactor allows to use high neutron wall loads and could eliminate frequent replacement of the first wall structure during reactor’s lifetime. Liquid wall should have a certain effective or optimum thickness to extend solid first wall lifetime to reactor’s lifetime and supply sufficient tritium for deuterium–tritium (DT) fusion driver. This study presents the effect of thickness of flowing liquid wall containing 90 mol % Flibe+10 mol % UF₄ or ThF₄ on the neutronic performance of a magnetic fusion reactor design called APEX. Neutron transport calculations were carried out with the aid of code Scale4.3. Numerical results brought out that optimum liquid wall thickness of ∼38 cm was found for the blankets using Flibe+10% UF₄ whereas, 56 cm for that with Flibe+10% ThF₄. Significant amount of high quality fissile fuel was produced by using heavy metal salt.