Some new volatile compounds from the non-enzymic browning reaction of glucose-glutamic acid system

Summary The volatile compounds from the Maillard reaction in the glucose - glutamic acid system were analysed by combined gas chromatography - mass spectrometry. Of the 50 peaks detected, 42 components comprising 2 acids, 2 alcohols, 5 carbonyls, 2 esters, 4 lactones, 17 furans, 4 pyrazines and 3 pyrroles were identified, four of which tentatively. Decadien 2,4-al, 2-n-pentyl furoate, 2-(2-fury()-pyrazine. -nonalactone, 2-(2-fury()-5- or 6-methylpyrazine were previously not reported to occur in heated sugar - amino acid browning systems. The new compound, 5-formyloxymethyl-2-furfural has apparently not yet been recorded in the chemical literature.The compound 5-acetoxymethyl-2-furfural had an aroma close to that of bread whereas 5-formyloxymethyl-2-furfural exhibited a very faint sweet burnt aroma.

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Einige neue flüchtige Verbindungen aus der nicht-enzymatischen Bräunungsreaktion des Glucose-Glutaminsäure-Systems

Zusammenfassung Die flüchtigen Verbindungen aus der Maillardreaktion des Glucose-Glutaminsäure-Systems wurde mit Hilfe der Gaschromatographie/Massenspektrometrie analysiert. Von den 50 nachgewiesenen Peaks wurden 42 identifiziert: 2 Säuren, 2 Alkohole, 5 Carbonyle, 2 Ester, 4 Lactone, 17 Furane, 4 Pyrazine, 3 Pyrrole und 4 weitere provisorisch. Deca-2,4-dienal, 2-n-Pentylfluorat, 2-(2-Furyl)-pyrazin, -Nonalacton, 2-(2-Furyl)-5 oder -6-Methylpyrazin wurden bisher nicht in dem erhitzten Zucker-Aminosäuren-Bräunungssystem registriert. Die neue Verbindung 5-Formyloxymethyl-2-furfural ist anscheinend noch nicht in der chemischen Literatur festgestellt worden. Die Verbindung 5-Acetoxymethyl-2-furfural hat an ein Brot erinnerndes Aroma, während die 5-Formyloxymethyl-2-furfural-Verbindung ein sehr schwaches süßlich-verbranntes Aroma aufweist.

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Taken in part from the Ph. D. thesis of the Senior Author     

An apparent double glass transition of polyphenylene sulfide in blends with polyarylate

Summary Injection molded blends of polyphenylene sulfide (PPS) and polyarylate (PAR) are phase separated as evidenced by transmission electron microscopy (TEM) micrographs and the existence of glass transition temperatures (T_g's) near 100 °C (PPS) and 190 °C (PAR). Upon annealing, blends that contain 15% to 40% by weight PPS exhibited unusual double glass transition temperatures (aside from PAR's T_g at 190 °C) at ca. 88 °C and 110 °C. These transitions coincide, respectively, with the T_g's of amorphous and crystalline PPS homopolymer. PPS crystallinity and average domain size distribution were found to be larger in the skin region than in the core region. It is believed that the double T_g's are brought about by different PPS domains with two types of amorphous material.     

Terminal composition control of a binary distillation column

Terminal composition control of a pilot scale binary distillation column operated under the control of an IBM 1800 digital computer has been studied for disturbances in feed flow rate. Conventional two point control, whereby the overhead composition is controlled by reflux flow rate and bottom composition by means of steam rate, was demonstrated to be unsatisfactory. Two alternate control systems, namely a noninteracting control system and a ratio control system were evaluated. The noninteracting control system was constructed from a transfer function representation of the distillation column dynamics, determined from a series of on-line pulse tests. The results show that a very significant improvement in the control of both compositions is achieved by using noninteracting control or the ratio control scheme suggested by Rijnsdorp compared to the behavior that results using conventional two point feedback control. However, the control performance obtained using noninteracting control was only marginally better than that using the ratio control scheme.     

Stability of tapioca chips fried in RBD palm olein treated with antioxidants

The effectiveness of tertiarybutylhydroquinone (TBHQ), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) in stabilizing tapioca chips was assessed by determining the peroxide andp-anisidine values, absorbances at 232 nm and 268 nm and the 18:2/16:0 ratios of oil extracted from tapioca chips. The order of effectiveness of the antioxidants in stabilizing the chips was found to be TBHQ > BHT > BHA. The order of effectiveness of antioxidants, TBHQ > BHT > BHA, was maintained for chips from corresponding 1st, 4th and 7th fryings. The loss of antioxidants during storage could not be directly related to oxidation parameters.     

Crafting the Compelling User Experience

This article provides an introduction to the usage of software engineering approaches and tools for the design of user experience (UE). This approach was developed for three main reasons: (a) to provide UE design teams a rigorous, methodical, encompassing method that can be applied throughout the entire product development cycle; (b) to provide designers a way to work with abstract concepts to establish the conceptual design of the system before progressing to the realization of the design to the appropriate platform; and (c) to communicate the intended design to the implementation team in a manner that is concise, complete, and familiar. The approach is the application of Unified Modeling Language concepts to describe users and the UE design rather than the technical architecture. It is believed that designing the UE design separately from the technical architecture will help ensure teams deliver a usable and delightful UE. The methods in this article have been applied to a handful of real-world projects in the last year and a half. Thus far, the application of software engineering approaches and tools have been found to be very powerful aids that have enabled the creation of highly useful Web experiences as well as software applications.

Our intent is to address the full gamut of issues involved in creating a total user experience (UE)-from discovery of users needs through high-level and low-level design, ensuring fidelity during development, and deployment, with a full assessment of how well the design meets users' needs. We believe that through a concerted use of such a rigorous approach we can greatly improve not only the UE of products we create, but also the experience of designing and developing them. We are not the only team taking this direction in UE design. It has become clear to many in our field that a more rigorous, thorough, and accurate approach to UE design is not only possible-it is necessary, for many of the same reasons that software engineers long ago embraced such practices. As we are evolving our approaches in other phases, this article focuses on the discovery and design phase activities.     

From Constrained to Unconstrained Maximum Agreement Subtree in Linear Time

We propose and study the Maximum Constrained Agreement Subtree (MCAST) problem, which is a variant of the classical Maximum Agreement Subtree (MAST) problem. Our problem allows users to apply their domain knowledge to control the construction of the agreement subtrees in order to get better results. We show that the MCAST problem can be reduced to the MAST problem in linear time and thus we have algorithms for MCAST with running times matching the fastest known algorithms for MAST. A preliminary version of this paper appears in the Proceedings of the Fifth Workshop on Algorithms in Bioinformatics (WABI 2005). Research of H.F. Ting is supported in part by Hong Kong RGC Grant HKU-7172/06E.     

A mathematical analysis of the effects of Hebbian learning rules on the dynamics and structure of discrete-time random recurrent neural networks

We present a mathematical analysis of the effects of Hebbian learning in random recurrent neural networks, with a generic Hebbian learning rule, including passive forgetting and different timescales, for neuronal activity and learning dynamics. Previous numerical work has reported that Hebbian learning drives the system from chaos to a steady state through a sequence of bifurcations. Here, we interpret these results mathematically and show that these effects, involving a complex coupling between neuronal dynamics and synaptic graph structure, can be analyzed using Jacobian matrices, which introduce both a structural and a dynamical point of view on neural network evolution. Furthermore, we show that sensitivity to a learned pattern is maximal when the largest Lyapunov exponent is close to 0. We discuss how neural networks may take advantage of this regime of high functional interest.