A census of semisymmetric cubic graphs on up to 768 vertices

A list is given of all semisymmetric (edge- but not vertex-transitive) connected finite cubic graphs of order up to 768. This list was determined by the authors using Goldschmidt's classification of finite primitive amalgams of index (3,3), and a computer algorithm for finding all normal subgroups of up to a given index in a finitely-presented group. The list includes several previously undiscovered graphs. For each graph in the list, a significant amount of information is provided, including its girth and diameter, the order of its automorphism group, the order and structure of a minimal edge-transitive group of automorphisms, its Goldschmidt type, stabiliser partitions, and other details about its quotients and covers. A summary of all known infinite families of semisymmetric cubic graphs is also given, together with explicit rules for their construction, and members of the list are identified with these. The special case of those graphs having K_1,3 as a normal quotient is investigated in detail. Supported in part by N.Z. Marsden Fund (grant no. UOA 124) and N.Z. Centres of Research Excellence Fund (grant no. UOA 201) Supported in part by “Ministrstvo za šolstvo, znanost in šport Slovenije”, research program no. 101-506. Supported in part by research projects no. Z1-4186-0101 and no. Z1-3124-0101. The fourth author would like to thank the University of Auckland for hospitality during his visit there in 2003.     

A new approach to predict the biological activity of molecules based on similarity of their interaction fields and the logP and logD values: application to auxins

The activity of a biological compound is dependent both on specific binding to a target receptor and its ADME (Absorption, Distribution, Metabolism, Excretion) properties. A challenge to predict biological activity is to consider both contributions simultaneously in deriving quantitative models. We present a novel approach to derive QSAR models combining similarity analysis of molecular interaction fields (MIFs) with prediction of logP and/or logD. This new classification method is applied to a set of about 100 compounds related to the auxin plant hormone. The classification based on similarity of their interaction fields is more successful for the indole than the phenoxy compounds. The classification of the phenoxy compounds is however improved by taking into account the influence of the logP and/or the logD values on biological activity. With the new combined method, the majority (8 out of 10) of the previously misclassified derivatives of phenoxy acetic acid are classified in accord with their bioassays. The recently determined crystal structure of the auxin-binding protein 1 (ABP1) enabled validation of our approach. The results of docking a few auxin related compounds with different biological activity to ABP1 correlate well with the classification based on similarity of MIFs only. Biological activity is, however, better predicted by a combined similarity of MIFs + logP/logD approach.     

High-performance liquid chromatographic determination of ochratoxin A and its 4R-4-hydroxy metabolite in human urine

One of the metabolites of ochratoxin A (OA) is 4R-4-hydroxyochratoxin A (4-OH-OA), and the ratio of 4-OH-OA to OA excreted in urine can be linked to the carcinogenic potential of this compound. As further support to the hypothesis that OA can be involved in Balkan endemic nephropathy and the associated urinary system tumours, it was decided to investigate the presence of these two compounds in the urine of affected populations. A sensitive method is described for the determination of the compounds at the 10 ng l-1 level. It involves extraction, two purification steps by column chromatography and high-performance liquid chromatography (HPLC), an analysis by HPLC and a confirmatory test by HPLC after derivatisation.     

“You have to get wet to learn how to swim” applied to bridging the gap between research into personnel scheduling and its implementation in practice

Personnel scheduling problems have attracted research interests for several decades. They have been considerably changed over time, accommodating a variety of constraints related to legal and organisation requirements, part-time staff, flexible hours of staff, staff preferences, etc. This led to a myriad of approaches developed for solving personnel scheduling problems including optimisation, meta-heuristics, artificial intelligence, decision-support, and also hybrids of these approaches. However, this still does not imply that this research has a large impact on practice and that state-of-the art models and algorithms are widely in use in organisations. One can find a reasonably large number of software packages that aim to assist in personnel scheduling. A classification of this software based on its purpose will be proposed, accompanied with a discussion about the level of support that this software offers to schedulers. A general conclusion is that the available software, with some exceptions, does not benefit from the wealth of developed models and methods. The remaining of the paper will provide insights into some characteristics of real-world scheduling problems that, in the author’s opinion, have not been given a due attention in the personnel scheduling research community yet and which could contribute to the enhancement of the implementation of research results in practice. Concluding remarks are that in order to bridge the gap that still exists between research into personnel scheduling and practice, we need to engage more with schedulers in practice and also with software developers; one may say we need to get wet if we want to learn how to swim.

     

Green pH- and magnetic-responsive hybrid hydrogels based on poly(methacrylic acid) and Eucalyptus wood nanocellulose for controlled release of ibuprofen

Cellulose - pH- and magnetic-sensitive hybrid hydrogels based on poly(methacrylic acid) (PMAA), nanocellulose (NC), carboxymethyl cellulose (CMC) and magnetite particles (MN) were prepared as...     

Characterization analysis of raw and pyrolyzed plane tree seed (Platanus orientalis L.) samples for its application in carbon capture and storage (CCS) technology

Journal of Thermal Analysis and Calorimetry - Raw and pyrolyzed samples of the plane tree seeds (PTS) were tested by various advanced analytical techniques including simultaneous TG-DSC technique,...     

Wave equation for generalized Zener model containing complex order fractional derivatives

We study waves in a viscoelastic rod whose constitutive equation is of generalized Zener type that contains fractional derivatives of complex order. The restrictions following from the Second Law of Thermodynamics are derived. The initial boundary value problem for such materials is formulated and solution is presented in the form of convolution. Two specific examples are analyzed.     

On reactive solute transport through a curved pipe

The transport of a reactive solute by diffusion and convection in a thin (or long) curved pipe is considered. Using asymptotic analysis with respect to the pipe’s thickness, the effective model for solute concentration is formally derived. A simple approximation is computed, showing explicitly the effects of the pipe’s geometry in nature and magnitude.     

Enantiomeric separations by means of nano‐LC

Enantiomers represent a class of compounds extensively investigated since they can show totally different behaviors when they interact with a chiral environment. Because of their identical chemical structure (they differ only in the spatial arrangement of the atoms in the molecule), the separation of optical isomers is a challenging task of analytical chemistry. So far employed methods for the separation of enantiomers are mainly based on chromatography. CE as well was considered as an analytical technique suitable for chiral separations, characterized by high efficiency and low consumption of reagent. Recently, miniaturization was introduced in LC to answer the needs to perform analyses in the minimum time, to use the smallest amount of samples and to reduce environmental pollution. Nano‐LC represents nowadays a valid alternative to the abovementioned conventional analytical techniques, and can be advantageously exploited for enantiomeric separation especially because it needs minute amounts of the chiral material necessary to carry out enantiomeric separations. This review describes the development and applications of nano‐LC in the field of chiral separations. The data reported in literature show its relevance for the study enantiomers‐chiral selectors interaction, as well as for application in pharmaceutical and clinical research.