Properties of wheat bran polyphenol oxidase

Polyphenol oxidase (PPO) obtained from wheat bran catalyzed the oxidation of 4-methyl catechol. Phenolic compounds found naturally in crude extract played role as an endogeneous substrate and activity of crude extract needed correction. Activity versus enzyme concentration gave a linear plot at high substrate concentration whereas a nonlinear plot was obtained at low substrate concentration which proved the presence of endogeneous substrate. Adsorption on celite and extraction with polyvinylpyrrolidone (PVPP) caused the removal of phenols. Adsorption of PPO on celite yielded a 4-fold increase in specific activity whereas extraction with PVPP yielded a 2.5-fold increase in specific activity compared to the crude extract. The kinetics of PPO catalyzed oxidation obeyed Michaelis-Menten model; Km and Vmax values were found as 218 mM and 99 microM/min, respectively. The enzyme was inhibited by ethyl alcohol, dithiothreitol (DTT) and isoproterenol and exhibited heat stability up to a temperature of 90 degrees C. The optimum pH of the enzyme was found to be 5.0.     

Moisture sorption isotherms of grape pestil and foamed grape pestil

Moisture sorption isotherms of grape pestil and foamed grape pestil were determined using the static gravimetric method at 10, 20 and 30 degrees C. The overall shape of the curves was typical of sugar-rich materials. The effect of temperature on moisture content in the lower aw range was not significant (P > 0.05). Four models, namely the Brunauer, Emmet and Teller (BET), the Guggenheim, Anderson and DeBoer (GAB) the Halsey and the Oswin, were evaluated to determine the best fit for the experimental data. The BET and GAB models fitted well the data of the samples in the temperature and water activity range studied. The Clausius-Clapeyron equation was used to evaluate the isosteric heats of sorption.     

Optimum Power Allocation for Single-User MIMO and Multi-User MIMO-MAC with Partial CSI

We consider both the single-user and the multi-user power allocation problems in MIMO systems, where the receiver side has the perfect channel state information (CSI), and the transmitter side has partial CSI, which is in the form of covariance feedback. In a single-user MIMO system, we consider an iterative algorithm that solves for the eigenvalues of the optimum transmit covariance matrix that maximizes the rate. The algorithm is based on enforcing the Karush-Kuhn-Tucker (KKT) optimality conditions of the optimization problem at each iteration. We prove that this algorithm converges to the unique global optimum power allocation when initiated at an arbitrary point. We, then, consider the multi-user generalization of the problem, which is to find the eigenvalues of the optimum transmit covariance matrices of all users that maximize the sum rate of the MIMO multiple access channel (MIMO-MAC). For this problem, we propose an algorithm that finds the unique optimum power allocation policies of all users. At a given iteration, the multi-user algorithm updates the power allocation of one user, given the power allocations of the rest of the users, and iterates over all users in a round-robin fashion. Finally, we make several suggestions that significantly improve the convergence rate of the proposed algorithms.     

Joint channel estimation and resource allocation for MIMO systems-part I: single-user analysis

Multiple antenna systems are known to provide very large data rates, when the perfect channel state information (CSI) is available at the receiver. However, this requires the receiver to perform a noise-free, multi-dimensional channel estimation, without using communication resources. In practice, any channel estimation is noisy and uses system resources. We shall examine the trade-off between improving channel estimation and increasing the achievable data rate. We consider transmitside correlated multi-input multi-output (MIMO) channels with block fading, where each block is divided into training and data transmission phases. The receiver has a noisy CSI that it obtains through a channel estimation process, while the transmitter has partial CSI in the form of covariance feedback. In Part I of this two-part paper, we consider the single-user case, and optimize the achievable rate jointly over parameters associated with the training phase and data transmission phase. In particular, we first choose the training signal to minimize the channel estimation error, and then, develop an iterative algorithm to solve for the optimum system resources such as time, power and spatial dimensions. Specifically, the algorithm finds the optimum training duration, the optimum allocation of power between training and data transmission phases, the optimum allocation of power over the antennas during the data transmission phase.     

Effect of minimal neutralization at optimal conditions on minor components and oxidation stability of sunflower oil

In this study, oxidatively stable minimal neutralized sunflower seed oils were produced using three chemicals (Ca(OH)₂, MgO, and Na₂SiO₃) under previously determined optimal process conditions. Lipid oxidation rates at these optimum conditions were compared to the oils neutralized with NaOH (0.20%, 40°C, 15 min). It was concluded that the oils neutralized by NaOH had the shortest hydroperoxide and hexanal lag phases, thus were the least stable oils. Oils neutralized by Ca(OH)₂, MgO, and Na₂SiO₃ had lower FFA and higher oxidative stability than oil neutralized by NaOH. The study focused on which weak alkaline has higher oxidation stability and minimum FFA content and maximum acceptable tocopherol content. The oil neutralized by Ca(OH)₂ had the lowest FFA value and highest total phenolics and α-tocopherol contents and it had better oxidative stability than oil neutralized by NaOH. It suggests that Ca(OH)₂ could be more effective in producing a high quality oil.     

Predicting effect of filler metals on solidification cracking susceptibility of 2024 Al and 6061 Al

ABSTRACT

The susceptibility to solidification cracking was predicted for aluminium welds of 2024 Al made with filler metals 2319, 4043 and 4145 Al and of 6061 Al made with filler metals 4043 (traditional) and 4943 Al (new, higher strength). The maximum |dT/d(f_S)^1/2| (T: temperature; f_S: fraction of solid) was used as the crack susceptibility index. In each case, the index was calculated using the weld metal composition based on the measured dilution level. The predicted crack susceptibility decreased in the order of 2319 Al, 4043 Al and 4145 Al for 2024 Al, and was similar between 4043 Al and 4943 Al for 6061 Al. These predictions agreed well with the experimental results of recent crack susceptibility tests of these welds.     

Variable Step-Size Constant Modulus Algorithm Employing Fuzzy Logic Controller

The Constant Modulus Algorithm (CMA), although it is the most commonly used blind equalization technique, converges very slowly. The convergence rate of the CMA is quite sensitive to the adjustment of the step size parameter used in the update equation as in the Least Mean Squares (LMS) algorithm. A novel approach in adjusting the step size of the CMA using the fuzzy logic based outer loop controller is presented in this paper. Inspired by successful works on the variable step size LMS algorithms, this work considers designing a training trajectory that it overcomes hurdles of an adaptive blind training via controlling the level of error power (LOEP) and trend of error power (TOEP) and then obtains a more robust training process for the simple CMA algorithm. The controller design involves with optimization of training speed and convergence rate using experience based linguistic rules that are generated as a part of FLC. The obtained results are compared with well-known versions of CMA; Conventional CMA, Normalized-CMA [Jones, IEEE conference record of the twenty-ninth asilomar conference on signals, systems and computers (Vol. 1, pp. 694–697), 1996], Modified-CMA [Chahed, et al., Canadian conference on electrical and computer engineering (Vol. 4, pp. 2111–2114), 2004], Soft Decision Directed-CMA (Chen, IEE Proceedings of Visual Image Signal Processing, 150, 312–320, 2003) for performance measure and validation.     

WATER ADSORPTION AND DRYING CHARACTERISTICS OF OKRA Hibiscus Esculentus L

Moisture adsorption characteristics of okra were evaluated at 10, 20, 30° C. Isotherms were found to be of type III. Monolayer moisture contents were evaluated with GAB model. Drying was carried out at 60, 70, 80° C and drying data were analysed to obtain diffusivity values from the period of first felling drying rate. Effective diffusivity increased with increasing temperature. Calculated values of the effective diffusivity showed an Arrhenius type temperature dependence.     

Determination of ofloxacin in human aqueous humour by high-performance liquid chromatography with fluorescence detection

This unusual pathology has not been described in the medical literature of the last ten years. A 39-year-old patient, affected by unilateral cryptorchidism, on the right side, and congenital inguinal hernia, reached the operating theatre suffering from occlusive intestinal syndrome, due to a clogged hernial sac. This clog was caused by a retracting testicle which in turn stopped the ileal ansa from slipping back in to the peritoneum. Through this case we can underline the excursus of such pathology, which isn't very frequent in the adult but can, nevertheless create a fairly serious pathology, often leading to neoplan.     

Extrusion cooking of barley flour and process parameter optimization by using response surface methodology

BACKGROUND: The nutritional profile of barley places it in a prime position for development of a new extruded–expanded snack food with health benefits. It was therefore the aim to investigate the effect of extrusion processing variables on system parameters (specific mechanical energy, die pressure and die melt temperature) and physical properties (expansion, bulk density, texture and color) of barley flour extrudates and to optimize processing conditions for production of extruded snack food from barley flour by response surface methodology. RESULTS: Barley flour with 219.7 g kg^?1 moisture content was extruded at different die temperatures (140–160 °C) and screw speeds (150–200 rpm) through a co‐rotating twin‐screw extruder. The system parameters as well as product responses were mainly dependent on temperature, whereas the screw speed imparted a lesser effect. Extrudates produced under extrusion conditions of 160 °C, 150 and 200 rpm and at 164 °C and 150 rpm had higher preference levels of appearance, taste, texture and overall acceptability than that of other selected extrudates for sensory analysis. The optimal conditions for minimum bulk density and desired textural characteristics and color of extrudates correspond to a temperature of 156 °C and screw speed of 166 rpm. CONCLUSION: The results suggested that use of barley flour in extruded snack products offers a desirable variation in diet and can take advantage of the nutritional quality of barley. Copyright © 2008 Society of Chemical Industry