The biogenic amines and bacterial changes of farmed rainbow trout (Oncorhynchus mykiss) stored in ice

The biogenic amine content and related bacterial changes (Pseudomonas spp., psychrotrophic and mesophilic counts) in whole farmed rainbow trout (Oncorhynchus mykiss) were monitored during ice storage for 18 days (at 0, 3, 6, 9, 12, 15 and 18 days). Levels of putrescine, cadaverine and histamine, and bacterial loads, increased (P < 0.05) during storage, but tyramine was not detected in any of the tested samples. Concentration of putrescine ranged from 0.4 initially to 8.97 μg/g, and psychrotrophic microorganisms were dominant. The best linear regressions (correlations) were for putrescine and Pseudomonas spp. and psychrotrophs (r = 0.98), and for cadaverine with Pseudomonas spp. (r = 0.82). Putrescine content was a good quality marker. Histamine was detected only at later stages of storage and was therefore less suitable than the other biogenic amines as freshness indicator.     

Relationship between Riser and Downcomer Gas Holdups in Semi‐batch Circulating Bubble Columns

Gas holdups were measured in a circulating bubble column (CBC) using air‐water system with various additives. The liquid volume in the gas separator affected downcomer gas holdup up to volume ratio equal to 6%. Presence of surface active agents, alcohols, solid particles had little effects on the gas holdups ?_gd — a?_gr relationships. The gas holdups relationships are theoretically related by a single parameter model ?_gd = a?_gr — a + 1, and empirically by two parameter model ?_gd = a?_gr — constant. The theoretical model yielded a values ? 0.45, while the empirical model yielded a values ? 1.16. Analogy between the two models (Contreras et al., 1998) will lead to incorrect conclusions.     

A high performance architecture for computing the time-frequency spectrum

To solve the problem of detecting and displaying the changes in the spectra of nonstationary signals, there are two possible approaches. Either one uses the same estimators as for the stationary signals, but one approach uses shorter-length data blocks during which the signal is assumed to be stationary, and the other one uses the same length data and applies a time-varying spectrum estimator that accounts for the nonstationarity. A time-varying spectrum estimator called a time-varying correlogram (TVC) is a well-known estimator of the time-frequency spectrum of a nonstationary signal. In this paper, a high performance VLSI architecture for computing TVC is proposed.     

Polyoxyethylene esters of fatty acids: an alternative synthetic route for high selectivity of monoesters

Esterification reaction of fatty acids with polyoxyethylenes has been studied in the presence of solid acid catalysts and the results are compared with those obtained with a classical homogeneous catalyst, p-toluene sulphonic acid. Solid acid catalysts showed very high selectivities for monoesters even under less favorable reaction conditions of 1:1 molar ratios of oleic acid to PEG. Excess amount of PEG is normally required to ensure high selectivity for monoesters in the presence of homogeneous catalysts. The yields for monoesters given by heterogeneous catalysts such as zeolites, HPA and nafion were comparable to that with p-toluene sulphonic acid after 24 h of reaction. Results suggest that solid acid catalysts are potential catalysts for selective synthesis of monoesters from oleic acids and PEG even under severe reaction conditions. A screening study of different solid acid catalysts showed ZSM-5, zeolite-β, and nafion to be better catalysts than zeolite USY and mordenite, the former giving higher selectivity and yield to monoesters. The results suggest that the most important parameters in optimization catalyst performance for monoesters production is the acid strength and less so on other properties such as shape selectivity and concentration of active sites.     

Prioritised best effort routing with four quality of service metrics applying the concept of the analytic hierarchy process

In this paper, a new approach that applies the concept of the Analytic Hierarchy Process (AHP) in the area of routing in communication networks is proposed. AHP is a well-known model in the area of decision making with multiple objectives. In addition, a new algorithm called Enhanced Best Effort Quality of Service Routing (QoS) with Multiple Prioritised Metrics is proposed for connection-oriented point-to-point communications. Four QoS metrics have been considered: delay, bandwidth, security and loss probability. The results presented and discussed in this paper are focussed on demonstrating the effects of metric prioritisation on the routing decisions. It is found that changing priority of a metric from 0 (the lowest priority) to 1 (the highest priority) applying the proposed algorithm improves the value of that metric by an average of (20–60)% for 90% of utilisation range.     

Tensile and elastic behavior of tencel continuous filaments

Tencel is a regenerated cellulose fiber produced using an environmentally‐responsible dry‐jet wet‐spinning process, which contributes to its excellent mechanical properties. In this study, the tensile properties of Tencel continuous filaments are characterized and the effect of twist on mechanical properties, including breaking load and extension, are considered. Peak strength was obtained in Tencel filaments of 140 t m^?1. The elastic behavior of Tencel monofilament was observed by assessing the recovery from strain‐induced energy and the elastic recovery was found to be low. Along with time dependency, Tencel has the ability to stabilize its deformed state by forming new crosslinks, and this influences the elastic behavior. In simple extension cycles, the same low elasticity was observed. Cumulative extension cycles were also performed to characterize the behavior of filaments subjected to repeated strain and to determine the resultant hysteresis effects. Permanent elongation was observed at 2% imposed strain, which suggests that the filament has low extensibility. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1496–1503, 2006     

Detection of genetically modified soy in processed foods sold commercially in Malaysia by PCR-based method

Regulations for the use and labeling of genetically modified organism (GMO) products and derived ingredients are being implemented worldwide, that demands reliable and accurate methods to detect GMO in raw materials and food products. In this study, polymerase chain reaction (PCR) method was established for monitoring products derived from GMO that are sold in the markets in Malaysia, which specifically amplify the 35S promoter, nos (nopaline synthase-terminator), EPSPS (5-enolpyruvylshikimate-3-phosphate synthase) and RRS (CTP/CP4EPSPS). Using this method, we investigated the incidence of genetically modified soy (GM-soy) and specifically the presence of roundup ready soy (RRS). All the soybean samples were evidenced by presence of the lectin gene. Out of 85 samples examined, the 18 positive GM samples were raw bean (9), tofu (8) and tempe (1) (a traditional Malay food). The results demonstrate for the first time the presence of GM-soy in Malaysian food products, reinforcing the need for the development of accurate quantitative methods for routine analyses.     

利用腐植酸消光值表征苔草泥炭的分解度指标

土壤科学技术在泥炭地、泥炭地特征、泥炭性质和泥炭地利用研究上已经开展了大量工作，特别是在评价泥炭作为植物生长基质的泥炭性质特征方面发挥了重要作用。本研究目的是通过对五个泥炭剖面不同深度泥炭样品的有机碳、总氯和腐植酸消光值与分解度值相比较，试图建立表征泥炭分解度的度量指标。结果表明：具有较高分解度的泥炭样品位于纵轴Er4／5附近，且具有较高的Er6／7值，而低分解度的泥炭远离Er4／5轴，而具有低Er6／7值。     

Comparison of Estimation Capabilities of the Artificial Neural Network with the Wavelet Neural Network in Lipase-Catalyzed Synthesis of Triethanolamine-Based Esterquats Cationic Surfactant

In this study, estimation capabilities of the artificial neural network (ANN) and the wavelet neural network (WNN) based on genetic algorithm were investigated in a synthesis process. An enzymatic reaction catalyzed by Novozym 435 was selected as the model synthesis process. The conversion of enzymatic reaction was investigated as a response of five independent variables; enzyme amount, reaction time, reaction temperature, substrates molar ratio and agitation speed in conjunction with an experimental design. After training of the artificial neurons in ANN and WNN, using the data of 30 experimental points, the products were used for estimation of the response of the 18 experimental points. Estimated responses were compared with the experimentally determined responses and prediction capabilities of ANN and WNN were determined. Performance assessment indicated that the WNN model possessed superior predictive ability than the ANN model, since a very close agreement between the experimental and the predicted values was obtained.