Flexible querying via if-sets

The traditional query languages used in database management systems require precise and unambiguous queries only. Fuzzy querying was introduced to relax this rigidity and allow the user more natural information retrieval. In this article we suggest how to enrich fuzzy querying by the use of IF-sets. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 587–597, 2007.     

Structure-reactivity of naphthenic acids in the ozonation process

Large volumes of oil sands process-affected water (OSPW) are produced in northern Alberta by the surface mining oil sands industry. Naphthenic acids (NAs) are a complex mixture of persistent organic acids that are believed to contribute to the toxicity of OSPW. In situ microbial biodegradation strategies are slow and not effective at eliminating chronic aquatic toxicity, thus there is a need to examine alternative remediation techniques. NAs with multiple rings and alkyl branching are most recalcitrant to microbial biodegradation, but here we hypothesized that these same structural features may lead to preferential degradation in the ozonation process. Total NA degradation increased with increasing pH for commercial NA solutions, suggesting a hydroxyl radical mechanism and that naturally alkaline OSPW would unlikely require pH adjustment prior to treatment. For commercial NAs and OSPW, NAs with more rings and more carbon (and more H atoms) were depleted most rapidly in the process. Relative rate measurements with binary mixtures of model NA compounds not only confirmed this structure reactivity but also indicated that alkyl branching patterns were an additional factor determining NA reactivity. The results demonstrate that ozonation is complementary to microbial biodegradation, and the process remains a promising water reclamation strategy for the oil sands industry.     

Crowd dynamics – being stuck

We consider a crowd of N persons trying to leave some area trough a small exit. The probability is calculated that an individual is able to withdraw from the crowd under one?s own steam. The problem is simulated within the generalized force model (D. Helbing, et al., Nature 407 (2000) 487), and all model parameters are taken from this paper. The results indicate, that in a crowd of 150 persons, this probability is not greater than ten percent. We also evaluate the number of helpers necessary to get the above probability of fifty percent.     

Generalized convolution as a tool for the multi-dimensional filtering tasks

In this paper the so-called generalized convolution, being in fact an adequate adaptation of the well known circular convolution concept to any invertible block-transform, is proposed, developed, and analysed. First the proposed idea is summarized for a one-dimensional case. Then it is extended to multidimensional problems. The presented generalized convolution concept is based on the earlier A-convolution. This idea is recalled at the beginning and a set of techniques for studying the dependence of the respective coefficients on the arbitrary transform, is suggested. The generalized convolution matrix, being an extension of that for the circular convolution, is introduced and adapted to an arbitrary invertible transform. The filtering problem is then defined and presented in the transform domain. The multidimensional analysis starts with two-dimensional problems, then it is continued with formulas for multidimensional filtering tasks. The paper is illustrated with examples computed for twenty carefully selected transforms. Among them are Haar, Hadamard, Hartley, Karhunen-Loeve and a family of 16 discrete trigonometric transforms.     

Calculations of J integrals around fractal defects in plates

This paper presents a method of analyzing fractal defects based on numerical calculations of J integrals. Two different constructions of fractal approximations are taken into consideration together with a comparison of the stability of the numerical simulations in both cases. The value of J integral provides information about the energy concentrated on the defect. The result was used to examine the relation between the energy and the measure of the defect. The simplest model indicates this relation to be linear. Nonetheless, the presented results suggest that not only the measure of the defect but also its orientation and configuration play a significant role in the energy distribution on the defect boundaries.     

Silica functionalized by pyridinecarboximidamides as a novel sorbent of heavy metals ions

ABSTRACT

Two novel sorbents, obtained as a result of surface modification of silica gel for the Cu(II), Co(II) and Ni(II) removal from aqueous solutions were proposed. For the modification, 3-chloropropyltrimethoxysilane, N’-hydroxy-N,N-dioctylpyridine-3-carboximidamide and N’-hydroxy-N,N-dioctylpyridine-4-carboximidamides were used. A series of basic tests on the sorption of Cu(II), Co(II) and Ni(II) were carried out and the presented results indicated that the novel sorbents were able to remove all tested metals ions from the aqueous solutions, and the removal efficiency was dependent on the functionalised agent structure, dosage, metal ions concentration and pH. The Langmuir model also assumed that a monolayer sorption occurred.     

Synthesis and adsorptive properties of sulfonated nanocomposites based on carbon-encapsulated iron nanoparticles and styrene-p-divinylbenzene copolymer

ABSTRACT

A method of the synthesis of novel magnetic nanocomposite adsorbent of Fe(III) from aqueous solutions is presented. The nanocomposites consisted of carbon-encapsulated iron nanoparticles and styrene-p-divinylbenzene copolymer. The adsorptive active sites were introduced via the post-synthesis sulfonation. The presented sulfonated magnetic nanocomposite adsorbents can be easily separated using permanent magnets and their adsorption performance was comparable to the commercially available ion-exchange resins. The determined maximum adsorption capacities were between 10.9 and 49.5 mg?g^?1, whilst the equilibrium was reached for the contact time lower than 60 minutes.     

Application of Multinomial Logistic Regression to Model the Impact of Rainfall Genesis on the Performance of Storm Overflows: Case Study

Water Resources Management - In this study, a mathematical model was proposed to analyze the performance of storm overflows. The model included the influence of rainfall genesis on the duration of...     

Lipid composition and cell surface hydrophobicity of Candida albicans influence the efficacy of fluconazole–gentamicin treatment

Adherence of the fungus, Candida albicans, to biotic (e.g. human tissues) and abiotic (e.g. catheters) surfaces can lead to emergence of opportunistic infections in humans. The process of adhesion and further biofilm development depends, in part, on cell surface hydrophobicity (CSH). In this study, we compared the resistance of C. albicans strains with different CSH to the most commonly prescribed antifungal drug, fluconazole, and the newly described synergistic combination, fluconazole and gentamicin. The hydrophobic strain was more resistant to fluconazole due to, among others, overexpression of the ERG11 gene encoding the fluconazole target protein (CYP51A1, Erg11p), which leads to overproduction of ergosterol in this strain. Additionally, the hydrophobic strain displayed high efflux activity of the multidrug resistance Cdr1 pump due to high expression of the CDR1 gene. On the other hand, the hydrophobic C. albicans strain was more susceptible to fluconazole–gentamicin combination because of its different effect on lipid content in the two strains. The combination resulted in ergosterol depletion with subsequent Cdr1p mislocalization and loss of activity in the hydrophobic strain. We propose that C. albicans strains with different CSH may possess altered lipid metabolism and consequently may differ in their response to treatment.