Unexpected products of the allyldiethylamine hydroformylation homogeneously catalyzed by rhodium complexes

Attempts to carry out the hydroformylation of allyldiethylamine homogeneously catalyzed by rhodium complexes led to unexpected formation of N,N,N,N-tetraethyl-1,4-diaminobutane and 4-(diethylamino)-1-butanole as final products. The role of the catalyst on the product formation and the reaction mechanism are briefly discussed.     

Modelling of the lignin peroxidase LIII of Phlebia radiata: use of a sequence template generated from a 3-D structure

A model of the lignin peroxidase LIII of Phlebia radiata wasconstructed on the basis of the structure of cytochrome c peroxidase(CCP). Because of the low percentage of amino acid identitybetween the CCP and the lignin peroxidase LIII of Phlebia radiata,alignment of the sequences was based on the generation of atemplate from a knowledge of the 3-D structure of CCP and consensussequences of lignin peroxidases. This approach gave an alignmentin which all the insertions in the lignin peroxidase were placedat loop regions of CCP, with a 21.1% identity for these twoproteins. The model was constructed using this alignment andthe computer program COMPOSER, which assembles the model asa series of rigid fragments derived from CCP and other proteins.Manual intervention was required for some of the longer loopregions. The -helices forming the structural framework, andespecially the haem environment of CCP, are conserved in theLIII model and the core is close packed without holes. A possiblesite of the substrate oxidation at the haem edge of LIII isdiscussed.     

Conceptual modelling of web sites for end-users

Internet and the WWW more and more play an important role in our information society. It is now one of the major sources of information in every rank of our society. The overwhelming accessibility to data, on a global scale, does not necessarily translate to widespread utility of data. We often find that we are drowning in data, with few tools to help managing relevant data for our various activities. In this paper, we argue that the WWW and its end-users could benefit from the existence of a conceptual web site schema. We propose such a conceptual web site schema that describes what information is available in a web site and how this information is structured into pages and links. To allow to communicate this information through the web, we developed an XML Document Type Definition (DTD) for this conceptual web site schema. We also illustrate the feasibility of the approach by a simple application program developed using the XML Document Object Model (DOM). This revised version was published online in August 2006 with corrections to the Cover Date.     

Spatial distribution and habitat characterization of schistosomiasis host snails in lake and land habitats of western Kenya

Intermediate host snails of schistosomiasis were surveyed in this study to determine their abundance and distribution in the lake and land aquatic habitats of Lake Victoria basin of Kenya. Several sites were sampled at eight locations, both in the lake and on the land. The habitat and/or vegetation type (i.e. open water, hippo grass, hyacinth, ambatch trees, other vegetation, stream, swamp, pond, dam) of the sampled aquatic sites within the locations were also differentiated, water physicochemical parameters were determined, and the abundance of different species or taxa of phytoplankton and zooplankton were enumerated and correlated with the abundance of schistosomiasis snails in the sites. The results indicated significantly more Biomphalaria sudanica snails than Bulinus africanus snails in different physical habitats on land (Student's t‐test, P < 0.05), as well as in different locations on land (Student's t‐test, P = 0.026). Regression analyses revealed that several physicochemical parameters, including dissolved oxygen (R² = ?0.659; n = 8; P = 0.014), pH (R² = 0.728; n = 8; P = 0.007) and turbulence (R² = ?0.616; n = 8; P = 0.02), were predictive of Biomphalaria spp. abundance, while pH (R² = 0.610; n = 8; P = 0.02) and turbulence (R² = ?0.578; n = 8; P = 0.028) were predictive of Bulinus spp. abundance in different locations in the lake. Cyanobacteria (R² = 0.638; n = 8; P = 0.02) and chlorophyceae (R² = ?0.50; n = 8; P = 0.05) were shown to be predictive of both Biomphalaria spp. and Bulinus spp. abundance in different locations in the lake. Zooplankton abundance varied significantly between different locations in the lake (One‐way anova , P < 0.001). Bosmina spp. were found to be predictive of both Biomphalaria spp. (R² = ?0.627; n = 8; P = 0.01) and Bulinus spp. (R² = ?0.50; n = 8; P = 0.05) in different locations in the lake. The results from this study will help inform policy regarding control measures for schistosomias and intermediate snail hosts in Lake Victoria waters, as well as in adjacent terrestrial aquatic habitats and even beyond.     

Rubber-assisted embossing of polymer thin films using molds with through-thickness microchannels

A flexible microfluidic chip is difficult to fabricate using the standard hot embossing technology. In this study, rubber-assisted embossing of polymer thin films using molds with through-thickness microchannels was investigated. The polymer film was thermoformed into the microchannels by rubber as a soft counter-tool. Different processing conditions, as well as material selections, affecting the thickness uniformity and replicated depth were examined. Results indicated that smoother surfaces on the embossed articles were created, and the thickness uniformity and the depth of the embossed channel were significantly affected by the embossing temperature, the embossing pressure, and the rubber hardness. The embossed film was sealed on one side with a layer of transparent adhesive film to form closed microchannels, and desired 3-D flow characteristics were obtained with this flexible microfluidic chip.     

Supervisory control synthesis of discrete-event systems using a coordination scheme

Supervisory control of distributed DES with a global specification and local supervisors is a difficult problem. For global specifications, the equivalent conditions for local control synthesis to equal global control synthesis may not be met. This paper formulates and solves a control synthesis problem for a generator with a global specification and with a combination of a coordinator and local controllers. Conditional controllability is proven to be an equivalent condition for the existence of such a coordinated controller. A procedure to compute the least restrictive solution within our coordination control architecture is provided and conditions under which the result coincides with the supremal controllable sublanguage are stated.     

A note on controllability of deterministic context-free systems

In this paper, we prove that the most important concept of supervisory control of discrete-event systems, the controllability property, is undecidable for two deterministic context-free languages $K$ and $L$, where $L$ is prefix closed, even though $K$ is a subset of $L$. If $K$ is not a subset of $L$, the undecidability follows from the work by Sreenivas. However, the case where $K$ is a subset of $L$ does not follow from that work because it is decidable whether $K$ and $L$ are equivalent as shown by Sénizergues. Thus, our result completes this study. The problem is also mentioned as open in the Ph.D. thesis by Griffin, who extended the supervisory control framework so that the specification language is modeled as a deterministic context-free language (compared to the classical approach where the specification is regular) and the plant language is regular. This approach is of interest because it brings an opportunity for more concise representations of the specification (as discussed, e.g., in the work by Geffert et al.) and, therefore, in some sense it treats the most interesting problem of current supervisory control theory, the state-space explosion problem.     

Media coverage in times of political crisis: A text mining approach

At the year end of 2011 Belgium formed a government, after a world record breaking period of 541 days of negotiations. We have gathered and analysed 68,000 related on-line news articles published in 2011 in Flemish newspapers. These articles were analysed by a custom-built expert system. The results of our text mining analyses show interesting differences in media coverage and votes for several political parties and politicians. With opinion mining, we are able to automatically detect the sentiment of each article, thereby allowing to visualise how the tone of reporting evolved throughout the year, on a party, politician and newspaper level. Our suggested framework introduces a generic text mining approach to analyse media coverage on political issues, including a set of methodological guidelines, evaluation metrics, as well as open source opinion mining tools. Since all analyses are based on automated text mining algorithms, an objective overview of the manner of reporting is provided. The analysis shows peaks of positive and negative sentiments during key moments in the negotiation process.