Volatiles of Fresh and Commercial Sweet Red Pepper Pastes: Processing Methods and Microwave Assisted Extraction

Microwave-assisted hexane or water extraction was used to extract flavor compounds from fresh red pepper fruit and also from traditionally and industrially made pepper pastes. The composition of the volatile components from each extract was analyzed using comprehensive two-dimensional gas chromatography with time of flight mass spectrometry. In total, 79 compounds were determined including 15 alcohols, 14 terpenes, 13 aldehydes, 12 ketones, 7 fatty acids, 6 fatty acid esters, and 6 browning reaction products. The major common compounds of fresh pepper and the pastes were 2-pentanone, 3-hexanol, acetic acid, oleic acid, and linoleic acid. The compounds (E)-2-undecenal, farnesol, 2-pentadecyn-1-ol, linolenic acid, and squalene were found only in the fresh pepper samples. Browning reaction products were observed in both of the pastes. However, their concentration was much higher in the industrially made one. Microwave-assisted hexane extraction from the traditionally made pepper paste gave the highest number of volatiles. Many volatiles considered to possess pleasant aroma characteristics were observed only in the traditionally made paste.     

Isolation of some luteolin derivatives from Mentha longifolia (L.) Hudson subsp. longifolia and determination of their genotoxic potencies

This study was designed to evaluate the mutagenic and antimutagenic activities of luteolin derivatives (luteolin 7-O-glucoside, luteolin 7-O-rutinoside and luteolin 7-O-glucuronide) isolated from Mentha longifolia (L.) Huds. subsp. longifolia by using Ames Salmonella test (TA 1535 and TA1537 strains). In the antimutagenicity assays, luteolin 7-O-glucoside, luteolin 7-O-rutinoside and luteolin 7-O-glucuronide showed antimutagenic effects on TA1537 and TA1535 strains. The highest inhibition rates for luteolin 7-O-glucoside, luteolin 7-O-rutinoside and luteolin 7-O-glucuronide on TA1537 strain were 84.03%, 87.63% and 67.77%, respectively. Similarly, in the antimutagenicity assays performed with the TA1535 strain, the inhibition rates for luteolin 7-O-glucoside and luteolin 7-O-rutinoside were 23.86% and 23.76% respectively. Our findings showed that the antimutagenic properties of luteolin derivatives on TA1537 and TA1535 strains have been found to be structure dependent. The clarification of differences in antimutagenic potency of these luteolin derivatives based on their structures has been demonstrated in this study.     

Analytical modeling and resource planning for cognitive radio systems

Cognitive radio heralds the next step in the evolution of wireless communications. In this paper, an analytical model for infrastructure based cognitive radio systems is proposed, and its performance is evaluated under bursty traffic scenarios in a multiple cell environment. Performance metrics like probabilities of dropping and blocking for primary and secondary users as well as forced termination and forced frequency handoff for secondary users are investigated, and the analytical model is verified with simulations. In addition to the analytical model, a new resource planning method is proposed to compensate for uneven traffic load distribution. The proposed method considers offered traffic, hop count to the heavily loaded cell, and velocity of mobile users during resource planning and performs better in terms of probability of blocking, dropping, and forced termination. The proposed method is promising in balancing the system performance measures, yet there is room for further improvement for finding a closed formula for the proposed analytical model. Copyright © 2010 John Wiley & Sons, Ltd.     

Antioxidant effect of essential oils of rosemary,clove and cinnamon on hazelnut and poppy oils

Antioxidant effects of essential oils from rosemary (Rosmarinus officinalis), clove (Syzygium aromaticum) and cinnamon (Cinnamomum zeylanicum) were determined on hazelnut and poppy oils. These essential oils were added to the oils at concentrations of 0.25% and 0.5%. Butylated hydroxyanisole (BHA) at 0.02% level served as standard besides the control groups for comparison. The samples were stored 50 °C in darkness for 14 days. The antioxidant activity of the essential oils was determined by measuring peroxide values (meq O₂/kg oil) at regular intervals. On the basis of peroxide value assay, the essential oils showed stronger antioxidant effect when compared to control groups. BHA was more effective than the essential oils, whilst it exhibited no antioxidative effect on the first few days of storage. Amongst the investigated essential oils, the cinnamon oil was the most effective on retarding lipid oxidation of crude oils, which was followed by clove and rosemary oils.     

Production of waste tyre oil and experimental investigation on combustion,engine performance and exhaust emissions

In this study, waste tyre was pyrolyzed at different conditions such as temperature, heating rate and inert purging gas (N₂) flow rate. Pyrolysis parameters were optimized. Optimum parameters were determined. The main objective of this study was to investigate combustion, performance and emissions of diesel and waste tyre oil fuel blend. Experimental investigation was performed in a single cylinder, direct injection, air cooled diesel engine at maximum engine torque speed of 2200 rpm and four different engine load including 3.75, 7.5, 11.25 and 15 Nm. The effects of waste tyre oil on combustion characteristics such as cylinder pressure, heat release rate, ignition delay (ID), combustion duration, engine performance were investigated. In-cylinder pressure and heat release rate increased with waste tyre oil fuel blend (W10) with the increase of engine load. In addition, ID was shortened with the increase of engine load for test fuels but it increased with the addition of waste tyre oil. Lower imep values were obtained because of the lower calorific value of waste tyre oil fuels. Maximum thermal efficiencies were determined as 28.27% and %25.12 with diesel and W10 respectively at 11.25 Nm engine load. When test results were examined, it was seen that waste tyre oil highly affected combustion characteristics, performance and emissions.     

Fabrication of Mo-modified carbon felt as candidate substrate for electrolysis: Optimization of pH,current and metal amount

Mo was electrochemically deposited over a carbon felt (C) support in order to enhance hydrogen evolution activity of the support and make it a candidate for further modifications. For this aim, the effects of pH of deposition bath solution, deposition current and amount of deposited Mo were studied and optimized. Hydrogen evolution activity of the electrodes was evaluated in 1 M KOH solution with the help of electrochemical techniques. Surface structures of the electrodes were examined by scanning electron microscopy (SEM). It was found that 1 g Mo/g C modified electrode at pH 6 and 50 mA current exhibits the best hydrogen releasing performance. The enhanced current density at this electrode under ?1.60 V(Ag/AgCl) was 59.6% with respect to the bare support, which demonstrates that modifying the support by a thin Mo layer favors the hydrogen evolution reaction (HER) and reduces the energy requirement. The high hydrogen evolution performance of this modified substrate was assigned to its excellent structure, large surface area as well as high intrinsic catalytic activity of Mo. According to experimental findings, the Mo-modified C substrate was suggested for preparation of further modified electrode materials, especially with trace amounts of precious metals.     

The application of seasonal latent variable in forecasting electricity demand as an alternative method

In this study, we used ARIMA, seasonal ARIMA (SARIMA) and alternatively the regression model with seasonal latent variable in forecasting electricity demand by using data that belongs to “Kayseri and Vicinity Electricity Joint-Stock Company” over the 1997:1–2005:12 periods. This study tries to examine the advantages of forecasting with ARIMA, SARIMA methods and with the model has seasonal latent variable to each other. The results support that ARIMA and SARIMA models are unsuccessful in forecasting electricity demand. The regression model with seasonal latent variable used in this study gives more successful results than ARIMA and SARIMA models because also this model can consider seasonal fluctuations and structural breaks.     

Water-in-Water Emulsion Based Synthesis of Hydrogel Nanospheres with Tunable Release Kinetics

Poly(ethylene glycol) (PEG) micro/nanospheres have several unique advantages as polymer based drug delivery systems (DDS) such as tunable size, large surface area to volume ratio, and colloidal stability. Emulsification is one of the widely used methods for facile synthesis of micro/nanospheres. Two-phase aqueous system based on polymer–polymer immiscibility is a novel approach for preparation of water-in-water (w/w) emulsions. This method is promising for the synthesis of PEG micro/nanospheres for biological systems, since the emulsion is aqueous and do not require organic solvents or surfactants. Here, we report the synthesis of nano-scale PEG hydrogel particles using w/w emulsions using phase separation of dextran and PEG prepolymer. Dynamic light scattering (DLS) and scaning electron microscopy (SEM) results demonstrated that nano-scale hydrogel spheres could be obtained with this approach. We investigated the release kinetics of a model drug, pregabalin (PGB) from PEG nanospheres and demonstrated the influence of polymerization conditions on loading and release of the drug as well as the morphology and size distribution of PEG nanospheres. The experimental drug release data was fitted to a stretched exponential function which suggested high correlation with experimental results to predict half-time and drug release rates from the model equation. The biocompatibility of nanospheres on human dermal fibroblasts using cell-survival assay suggested that PEG nanospheres with altered concentrations are non-toxic, and can be considered for controlled drug/molecule delivery.     

Photophysics of Molecular‐Weight‐Induced Losses in Indacenodithienothiophene‐Based Solar Cells

The photovoltaic performance and optoelectronic properties of a donor–acceptor copolymer are reported based on indacenodithienothiophene (IDTT) and 2,3‐bis(3‐(octyloxy)phenyl)quinoxaline moieties (PIDTTQ) as a function of the number‐average molecular weight (M_n). Current–voltage measurements and photoinduced charge carrier extraction by linear increasing voltage (photo‐CELIV) reveal improved charge generation and charge transport properties in these high band gap systems with increasing M_n, while polymers with low molecular weight suffer from diminished charge carrier extraction because of low mobility–lifetime (μτ) product. By combining Fourier‐transform photocurrent spectroscopy (FTPS) with electroluminscence spectroscopy, it is demonstrate that increasing M_n reduces the nonradiative recombination losses. Solar cells based on PIDTTQ with M_n = 58 kD feature a power conversion efficiency of 6.0% and a charge carrier mobility of 2.1 × 10^?4 cm² V^?1 s^?1 when doctor bladed in air, without the need for thermal treatment. This study exhibits the strong correlations between polymer fractionation and its optoelectronics characteristics, which informs the polymer design rules toward highly efficient organic solar cells.     

Application of neural networks to heuristic scheduling algorithms

This paper considers the use of artificial neural networks (ANNs) to model six different heuristic algorithms applied to the n job, m machine real flowshop scheduling problem with the objective of minimizing makespan. The objective is to obtain six ANN models to be used for the prediction of the completion times for each job processed on each machine and to introduce the fuzziness of scheduling information into flowshop scheduling. Fuzzy membership functions are generated for completion, job waiting and machine idle times. Different methods are proposed to obtain the fuzzy parameters. To model the functional relation between the input and output variables, multilayered feedforward networks (MFNs) trained with error backpropagation learning rule are used. The trained network is able to apply the learnt relationship to new problems. In this paper, an implementation alternative to the existing heuristic algorithms is provided. Once the network is trained adequately, it can provide an outcome (solution) faster than conventional iterative methods by its generalizing property. The results obtained from the study can be extended to solve the scheduling problems in the area of manufacturing.