Swelling behavior of poly(acrylamide‐co‐N‐vinylimidazole) hydrogels under different environment conditions

A series of random copolymers of acrylamide and N‐vinylimidazole, poly(AAm‐co‐NVI), with various compositions were prepared using redox copolymerization. The influence of environmental conditions such as pH, temperature, and ionic strength on the swelling behavior of the copolymeric hydrogels was investigated. The hydrogels exhibited the highest equilibrium swelling in basic medium at high temperature. Equilibrium swelling decreased with rising ionic strength at pH 5.0. As pH increased, equilibrium swelling of the hydrogels increased at pH 11.0 and I = 0.20 M. Swelling kinetics of the hydrogels was found to be non‐Fickian at 25°C. The process tended to be Fickian at higher pH and temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1783–1788, 2005     

IOT Based Augmented Perturb-and-Observe Soft Switching Boost Converters for Photovoltaic Power Systems in Smart Cities

This paper focuses on IOT based soft switching boost converter based solar energy applications for smart cities and making cities smarter and greener around the globe. It presents one of the applications of the Internet of Things to design and implementation of a highly efficient boost converter used for powering the Arduino and the Bluetooth device for controlling the switching of the led and buzzer by using smart city applications. The soft switching boost converter is essential to maximize the low-level voltage obtained from the solar board to the enhanced voltage conversion ratio for the efficient electric power generation. In this paper, the three separate methodologies of DC–DC boost converters with additional resonant/snubber circuit and resistive load associated with solar panel modules proposed with maximum power point tracking (MPPT) control. The MPPT is obtained by modified augmented perturb and observe algorithm. IoT helps Smart City(SC) systems to support various network functions throughout the generation, transmission, distribution and consumption of energy by incorporating IoT devices (such as sensors, actuators and smart meters), as well as by providing the connectivity, automation and tracking for such devices. It is utilized to extract the most extreme power from solar panel by controlling the duty ratio of the suggested soft switching based boost converter. In this paper a smart IOT system is used to control and monitoring the effect of reference power variations, parameter values to the voltage control to the converter. The solar panel, boost converter and the MPPT is modeled using MATLAB/SIMULINK environment and reach the power transfer efficiency up to 97%.     

Effect of thermochemical sludge pretreatment on sludge reduction and on performances of anoxic‐aerobic membrane bioreactor treating low strength domestic wastewater

BACKGROUND: Reduction of excess sludge production has become an urgent issue. An investigation into the influence of thermochemical sludge pretreatment on sludge reduction in a bench‐scale anoxic‐aerobic membrane bioreactor was performed. Two systems were operated. In one system, part of the mixed liquid (1.5% of the influent flow rate) was pretreated thermochemically (at 80 °C, pH 11 and 3 h) and returned to the bioreactor. This study examined and evaluated the effect of thermochemical sludge pretreatment on the reduction of excess sludge and on the performance of the system. RESULTS: The average solubilization efficiency of the pretreated sludge was found to be about 0.2. The sludge production rate of the experimental system (E‐MBR) was less than that of the control (C‐MBR) by about 33%. The total phosphorus was removed mainly by normal cell synthesis, with removal efficiencies of 38–40% and 40–42% for the E‐MBR and C‐MBR, respectively. The total nitrogen removal in the E‐MBR was slightly higher than in the C‐MBR due to supply of soluble chemical oxygen demand (SCOD) from the digested sludge solution as an external carbon source. The mixed liquor volatile suspended solids (MLVSS) and mixed liquor suspended solids (MLSS) ratios for the two systems were almost identical, in the range 74–77%, indicating that the inorganics from the disintegrated cells do not accumulate as particulates in the reactor. The TMP was maintained at less than 6 cmHg for 180 days without membrane cleaning. CONCLUSION: Thermochemical sludge pretreatment can play an important role in reducing sludge production. The qualities of the effluent water were not significantly affected during 6 months of operation. Copyright © 2009 Society of Chemical Industry     

Enhanced luminescence in CaMoO4: Eu3+ red phosphor nanoparticles prepared by mechanochemically assisted solid state meta-thesis reaction method

For the first time, CaMoO₄: xEu³⁺ (x = 0.02, 0.04, 0.06, 0.08, 0.1) red phosphor nanoparticles were synthesized using the simple mechanochemically assisted solid state meta-thesis (SSM) reaction method and the luminescence properties as a function of Eu³⁺ ion concentration was investigated. The characteristics of the phosphor materials were analyzed using X-ray diffraction, fourier transform infrared spectroscopy, photoluminescence (PL) and diffuse reflectance spectroscopy. For 8 mol% of Eu³⁺ concentration, the phosphor shows an intensified excitation peak at 392 nm indicating a strong absorption. The PL emission spectra of CaMoO₄: Eu³⁺ phosphors showed an intense peak at 615 nm (red) which corresponds to ⁵D₀ → ⁷F₂ transition of Eu³⁺. The optimal Eu³⁺ concentration in CaMoO₄ phosphors for enhanced red emission occurs for 8 mol% and above this concentration, the emission intensity decreases due to quenching effect. The CIE colour coordinates of the CaMoO₄: 0.08Eu³⁺ red phosphor coincide very well with the standard values of NTSC. The red emission intensity of the SSM prepared CaMoO₄: 0.08Eu³⁺ red phosphor is 4.7 times greater than that of the commercial Y₂O₂S: Eu³⁺ red phosphor and 1.6 times more than the same phosphor prepared by the solid state reaction method.     

Enzymatic esterification of (−)-menthol with lauric acid in isooctane by sorbitan monostearate-coated lipase from Candida rugosa

Esterification of (−)-menthol and (±)-menthol with lauric acid in isooctane was successfully catalyzed by a commercial nonioic surfactant (sorbitan monosterate)-coated lipase from Candida rugosa (Lipase AY “Amano” 30) at the molar ratio of 1∶1 and at 35°C using 1.5 g enzyme/g (−)-menthol and 0.1-g molecular sieves. After 1 h, molar conversion of (−)-menthol reached 81%. Equilibrium was reached after ca. 4 h, giving a (−)-menthol molar conversion of 94%. Under the same conditions, native lipase catalyzed the esterification of (−)-menthol and lauric acid to yield a molar conversion of 93% after 72 h. Coating the lipase with sorbitan monosterate increased the esterification rates of both (−)-menthol and (±)-menthol with lauric acid. After 6 h, the molar conversions of (−)-menthol and (±)-menthol were 94, and 62%, respectively.     

A Comparison of Variational and Genetic Algorithm Performances in the Optimization of a Polymerization Process

The aim of this work is to compare the performances of two well‐known methods, Minimum Principle and Genetic Algorithm, in the optimization of the methyl methacrylate polymerization process in solution. In order to select a kinetic model for this process, the published kinetic models were reviewed and compared by simulation in similar operating conditions. Based on the kinetic model proposed by Baillagou and Soong (1985), the temperature profile necessary to attain, in a given reaction time, specified values for monomer conversion, number‐average molecular weight and polydispersity index, was calculated. The temperature profiles calculated by the two optimization algorithms are practically identical, but they are obtained with different computational efforts. The results of this comparison are used to draw several conclusions regarding the proficiency of the two methods in the optimization of complex reaction processes.     

Probing thermal behaviour of microbial transglutaminase with fluorescence and in silico methods

BACKGROUND: Knowledge of transglutaminase behaviour at thermal treatment allows efficient applications in food processing. The heat‐induced conformational changes of microbial transglutaminase were studied by fluorescence spectroscopy and a molecular modelling approach. RESULTS: The experimental results indicate the unfolding of transglutaminase in a single‐phase reaction, at temperatures over 60 °C. The incidence of conformational changes is also supported by the increase of both intrinsic and 1‐anilino‐8‐naphthalene sulfonate fluorescence intensity with temperature. Changes in the secondary and tertiary structure of transglutaminase were outlined after running molecular dynamics simulations at temperatures ranging from 25 °C to 80 °C. CONCLUSION: The motif's particularities varied with the temperature, suggesting structural rearrangements of the protein, mainly in helices. The largest deviation from the structure equilibrated at 25 °C was observed at 80 °C. © 2012 Society of Chemical Industry     

Synthesis and Characterization of Polyacetylene with Side-chain Thiophene Functionality

A new polyacetylene derivative with electroactive thiophene substituent, namely poly(2-methylbut-2-enyl thiophene-3-carboxylate) was synthesized and characterized. For this purpose, novel acetylene monomer was synthesized by the reaction of 3-thiophenecarboxylic acid with propargyl bromide and polymerized with a Rh catalyst to give the corresponding polymer. The chemical structure of the polymer was characterized to comprise the conjugated backbone and electroactive thiophene side group. UV spectral changes of the polymer with temperature were also studied. The polymer exhibited better thermal stability than the unsubstituted polyacetylenes.