Objectives WGS-based antimicrobial susceptibility testing (AST) is as reliable as phenotypic AST for several antimicrobial/bacterial species combinations. However, routine use of WGS-based AST is hindered by the need for bioinformatics skills and knowledge of antimicrobial resistance (AMR) determinants to operate the vast majority of tools developed to date. By leveraging on ResFinder and PointFinder, two freely accessible tools that can also assist users without bioinformatics skills, we aimed at increasing their speed and providing an easily interpretable antibiogram as output. Methods The ResFinder code was re-written to process raw reads and use Kmer-based alignment. The existing ResFinder and PointFinder databases were revised and expanded. Additional databases were developed including a genotype-to-phenotype key associating each AMR determinant with a phenotype at the antimicrobial compound level, and species-specific panels for in silico antibiograms. ResFinder 4.0 was validated using Escherichia coli (n = 584), Salmonella spp. (n = 1081), Campylobacter jejuni (n = 239), Enterococcus faecium (n = 106), Enterococcus faecalis (n = 50) and Staphylococcus aureus (n = 163) exhibiting different AST profiles, and from different human and animal sources and geographical origins. Results Genotype–phenotype concordance was ≥95% for 46/51 and 25/32 of the antimicrobial/species combinations evaluated for Gram-negative and Gram-positive bacteria, respectively. When genotype–phenotype concordance was <95%, discrepancies were mainly linked to criteria for interpretation of phenotypic tests and suboptimal sequence quality, and not to ResFinder 4.0 performance. Conclusions WGS-based AST using ResFinder 4.0 provides in silico antibiograms as reliable as those obtained by phenotypic AST at least for the bacterial species/antimicrobial agents of major public health relevance considered.

Using a laser tweezers method, we have determined the long-range repulsive force as a function of separation between two charged, spherical polystyrene particles (2.7 microm diameter) present at a nonpolar oil-water interface. At large separations (6 to 12 microm between particle centers) the force is found to decay with distance to the power -4 and is insensitive to the ionic strength of the aqueous phase. The results are consistent with a model in which the repulsion arises primarily from the presence of a very small residual electric charge at the particle-oil interface. This charge corresponds to a fractional dissociation of the total ionizable (sulfate) groups present at the particle-oil surface of approximately 3 x 10(-4).

Vertical emulsion films with particle monolayers at their surfaces have been studied by direct microscope observations. The effects of particle wettability and surface coverage on the structure and stability of water films in octane and octane films in water have been investigated. Monodisperse silica particles (3 microm in diameter) hydrophobized to different extents have been used. It is found that the structure and stability of emulsion films strongly depend on the film type (water-in-oil or oil-in-water), the particle contact angle, the interactions between particles from the same and the opposite monolayer, and the monolayer density. Stable films are observed only when the particle wettability fulfills the condition for stable particle bridges--in agreement with the concept that hydrophilic particles can give stable oil-in-water emulsions, whereas hydrophobic ones give water-in-oil emulsions. In the case of water films with dilute disordered monolayers at their surfaces, the hydrophilic particles are expelled from the film center toward its periphery, giving a dimple surrounded by a ring of particles bridging the film surfaces. In contrast, the thinning of octane films with dilute ordered monolayers at their surfaces finally leads to the spontaneous formation of a dense crystalline monolayer of hydrophobic particles bridging both surfaces at the center of the film. The behaviors of water and octane films with dense close-packed particle monolayers at their surfaces are very similar. In both cases, a transition from bilayer to bridging monolayer is observed at rather low capillary pressures. The implications of the above finding for particle stabilized emulsions are discussed.

We examine the possible use of Description Logics as a knowledge representation and reasoning system for high-level scene interpretation. It is shown that aggregates composed of multiple parts and constrained primarily by temporal and spatial relations can be used to represent high-level concepts such as object configurations, occurrences, events and episodes. Scene interpretation is modelled as a stepwise process which exploits the taxonomical and compositional relations between aggregate concepts while incorporating visual evidence and contextual information. It is shown that aggregates can be represented by a Description Logic ALCF(D) which provides feature chains and a concrete domain extension for quantitative temporal and spatial constraints. Reasoning services of the DL system can be used as building blocks for the interpretation process, but additional information is required to generate preferred interpretations. A probabilistic model is sketched which can be integrated with the knowledge-based framework.

The aggregation behaviour of aqueous solutions of the azo dye Acid Red 266 has been investigated by a combination of three di †erent analytical methods : 19F NMR, UV/Vis spectroscopy, and static light scattering (SLS). For a better comparison the same range of concentration was studied by all three methods. The NMR data were interpreted in terms of a monomer/dimer equilibrium and, additionally, of a monomer/n-merequilibrium, based on an isodesmic model. No distinction between both equilibria was possible. Modelling the UV/Vis data by a monomer/dimer equilibrium gives access to all of the important thermodynamic quantities associated with a dimerization. The major driving force for aggregation is enthalpic with *H D \ [22.10 kJ mol~1, whereas a positive entropy of 7 J mol~1 K~1 points to a solvent contribution. The value of ^0.50 the free dimerization enthalpy is in good agreement with that from NMR results. Furthermore, the UV/Vis data revealed information on the local arrangement of the nearest neighbours in the dyestu † aggregates. The constituting molecules are separated by an interplanar distance of 0.69 nm and are twisted against each other by an angle of 50¡ (calculated from exciton theory). This twist angle proves that the group of one Acid CF 3 Red 266 molecule must be covered by an adjacent benzene ring within the aggregate and supports the conclusion obtained from NMR measurements. Both spectroscopic methods indicate a vertical stacking of the dye molecules, conÐrming a columnar structure of the aggregates. In contrast, SLS indicates the existence of highly aggregated species in dilute solutions of 10~6È10~4 mol L~1 with molecular weights and contour lengths in the order of magnitude of 105È106, and up to 700 nm, respectively. In addition to aggregation numbers, the overall shape of the aggregates were supplemented by SLS, suggesting a worm-like structure. Both, the contour lengths and the cross sections of the aggregates can be modiÐed by addition of electrolyte, resulting in an increase of chain sti †ness. Finally, the apparent discrepancies between the results of the spectroscopic methods and of SLS are discussed.

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In this work, the aggregation behavior of the cyanine dye, pseudoisocyanine chloride, in aqueous solutions both in the absence and presence of added electrolyte (0.01 M NaCl) was studied by a combination of UV/ vis spectroscopy and static light scattering (SLS). In the case of pure aqueous dyestuff solutions, an apparent aggregation number of N app ∼ 3 was found. A correction of the apparent molecular weights, M W,app , for the amount of the still present residual monomers gave only slightly larger values (N ∼ 4). However, it could be shown that, in the presence of 0.01 M NaCl at low dyestuff concentration (0.75 × 10 -3 mol L -1 ), the absorption spectrum shows the typical features of what is commonly believed to represent a dimer spectrum, whereas the corresponding SLS data unequivocally prove the existence of larger aggregates, consisting of at least 30 molecules. At higher dyestuff concentrations (∼2 × 10 -3 mol L -1 ) and in the presence of salt, apparent aggregation numbers of ∼1000 (uncorrected) and ∼2000 (corrected for c M ) were obtained. A particle form factor analysis of the SLS data by means of the Koyama approximation revealed typical wormlike aggregate structures for the higher concentration solutions. Additionally, the linear mass densities could be obtained at large scattering vectors and from those the number of molecules per unit length. They range from 1 to 2 nm -1 (uncorrected) and 2 to 6 nm -1 (corrected for c M ) and are consistent with a bundle formation of single aggregated strands. This is in agreement with recent cryo-transmission electron microscopy results obtained for the same compound.

There have been reports, originally by the Bristol group, and subsequently by others, of the preparation and properties of emulsions of stable, nearly monodisperse droplets of poly(dimethylsiloxane) (PDMS) in water, where no added surfactant is used. It has been assumed that their stability is due to the high density of surface-ionized hydroxyl groups, similar in fact to the closely related Stöber silica particles. In this study we confirm, from droplet lifetime studies, that droplets, prepared from such synthesized PDMS, are significantly more stable to coalescence than similar-sized droplets prepared from three types of commercially available PDMS, containing HO-, MeO-, or Me3-terminated chains, respectively. It is shown, however, that the zeta potentials of the synthesized PDMS and of the various commercial oils are all very similar (as indeed are their Hamaker constants). So some other explanation must be inferred for the enhanced stability to coalescence of the synthesized PDMS droplets compared to the commercial PDMS droplets. It is shown, for droplets formed from n-hexane and the synthesized oil, that stability to coalescence is conferred at PDMS volume fractions (phiPDMS) around 0.2 in the mixture. The synthesized PDMS is known to consist of mixtures of cyclic PDMS and short-chain linear species, with terminal -OH groups. There is some (indirect) evidence that in the interval 0.25 < phiPDMS < 0.35, the linear PDMS chains may be adsorbed close to a monolayer at the mixed oil/water interface, possibly conferring some enhanced Gibbs elasticity to the interface. This underpins the possibility that, in the synthesized oil droplets themselves, there is also preferential adsorption of the linear chains at the PDMS/water interface, and this leads to a value of the Gibbs elasticity, sufficient to significantly reduce coalescence. Unfortunately, the Gibbs elasticity could not be measured in this case. However, such preferential adsorption is unlikely to occur with the commercial PDMS oils, which are not so heterogeneous. Finally, it is shown that droplets of the three commercial PDMS oils could be stabilized against coalescence, if a sufficient, minimum amount of sodium dodecyl sulfate (SDS) is added. Gibbs elasticity values have been estimated in these cases, from plots of interfacial tension against ln(SDS concentration).