Screening of marine microalgae for biodiesel feedstock

Biodiesel production from microalgae lipids is increasingly regarded as a more sustainable and feasible alternative to conventional biodiesel feedstocks derived from terrestrial bioenergy crops. A total of ninety-six strains of marine microalgae, with an elevated biomass productivity and intracellular lipid content, were isolated from the coastal waters of Singapore using an automated flow cytometric cell-sorting technique. Cell sorting was based on the two-dimensional distribution of algal cells for red fluorescence (representing chlorophyll auto-fluorescence) against forward-light scatter (representing cell size) and red vs. green fluorescence. Twenty-one of the strains were further characterized with respect to cell growth rate, biomass concentration, lipid content (total and neutral lipid) and fatty acid profile. The growth rates of Skeletonema costatum, Chaetoceros and Thalassiosira species were greatest among the entire strains, but in terms of absolute lipid yield Nannochloropsis strains predominated. Nannochloropsis strains had a lipid content ranging from 39.4% to 44.9% of dry weight biomass. Transesterification of the lipids yielded 25-51% of fatty acid methyl ester (FAME) i.e. biodiesel, where total FAME content ranged between 11 and 21% of dry weight biomass. This study describes the microalgae screening process and demonstrates that Nannochloropsis is a promising species for biodiesel feedstock.     

A quasi-3D hyperbolic shear deformation theory for functionally graded plates

A quasi-3D hyperbolic shear deformation theory for functionally graded plates is developed. The theory accounts for both shear deformation and thickness-stretching effects by a hyperbolic variation of all displacements across the thickness, and satisfies the stress-free boundary conditions on the top and bottom surfaces of the plate without requiring any shear correction factor. The benefit of the present theory is that it contains a smaller number of unknowns and governing equations than the existing quasi-3D theories, but its solutions compare well with 3D and quasi-3D solutions. Equations of motion are derived from the Hamilton principle. Analytical solutions for bending and free vibration problems are obtained for simply supported plates. Numerical examples are presented to verify the accuracy of the present theory.     

Improvement of adherence and anticorrosion properties of an epoxy-polyamide coating on steel by incorporation of an indole-3 butyric acid-modified nanomagnetite

In this study, synthesized magnetite (Fe₃O₄) nanoparticles were treated with a corrosion inhibitor, indole-3 butyric acid (IBA) and incorporated in an epoxy-polyamide coating. The coating was applied on a carbon steel substrate. For comparison, coatings without particles or with nontreated Fe₃O₄ particles were also prepared. The IBA-modified nanomagnetite (IBA–Fe₃O₄) was characterized by infrared spectroscopy and Zeta potential measurements. The inhibitive action of IBA was shown by electrochemical measurements (polarization curves) performed for a bare carbon steel in 0.1 M NaCl solution containing Fe₃O₄ or IBA–Fe₃O₄ nanoparticles. Adherence and anticorrosion properties of the epoxy-based coatings containing Fe₃O₄ or IBA–Fe₃O₄ were compared to those of the pure epoxy-polyamide resin by dry and wet adherence measurements and by salt spray test. The results showed significant improvement of the film adherence and higher corrosion protection of the carbon steel in the presence of IBA–Fe₃O₄. It was concluded that the IBA effect was restricted to the metal/coating interface.     

Analytische und technologische Einflüsse auf das13C/12C-Isotopenverhältnis von Orangenöl-Komponenten

The influence of Chromatographic and technological procedures on the¹³C-isotope value of flavour compounds from orange oils was investigated. In order to avoid misinterpretations of isotopic data, quantitative yields during sample clean-up must be ascertained. Ordinary as well as deterpenated orange oils were not influenced by the technological processing. In the case of special products containing single compounds concentrated up to more than 70%, a shift in the¹³C/¹²C-isotope ratio was detectable.     

Effect of boundary conditions on the propagation of a vapor explosion in stratified molten tin/water systems

The propagation of a vapor explosion in a stratified molten tin/water system has been investigated experimentally in two different geometrical configurations: (i) linear propagation within a narrow channel, and (ii) radial propagation in a cylindrical tank. In the narrow channel experiments, self-sustained spatial propagation of the interaction occurs with an average propagation speed of 40–50 m s⁻¹ and with an effective mixing depth not more than 2 mm. A minimum degree of inertial confinement provided by the water aboe the tin as well as the confinement provided by the lateral walls are required to sustain a propagating interaction. If an interaction propagating within a narrow channel encounters a sudden increase in the channel width, it fails abruptly after a short distance. Interactions initiated in a relatively unconfined cylindrical geometry always fail to propagate after a certain distance. A comparison between the energetics of single molten tin drop interactions and interactions in the stratified systems suggests that similar dynamic processes occur during the first interaction cycle in each case. In both cases, the first interaction is an efficient method for mixing the tin and water and is often a precursor to a second, more violent interaction.     

Spatiotemporal structure in large neuronal networks detected from cross-correlation

The analysis of neuronal information involves the detection of spatiotemporal relations between neuronal discharges. We propose a method that is based on the positions (phase offsets) of the central peaks obtained from pairwise cross-correlation histograms. Data complexity is reduced to a one-dimensional representation by using redundancies in the measured phase offsets such that each unit is assigned a "preferred firing time" relative to the other units in the group. We propose two procedures to examine the applicability of this method to experimental data sets. In addition, we propose methods that help the investigation of dynamical changes in the preferred firing times of the units. All methods are applied to a sample data set obtained from cat visual cortex.     

Rodin: an open toolset for modelling and reasoning in Event-B

Event-B is a formal method for system-level modelling and analysis. Key features of Event-B are the use of set theory as a modelling notation, the use of refinement to represent systems at different abstraction levels and the use of mathematical proof to verify consistency between refinement levels. In this article we present the Rodin modelling tool that seamlessly integrates modelling and proving. We outline how the Event-B language was designed to facilitate proof and how the tool has been designed to support changes to models while minimising the impact of changes on existing proofs. We outline the important features of the prover architecture and explain how well-definedness is treated. The tool is extensible and configurable so that it can be adapted more easily to different application domains and development methods.     

Dynamic combinatorial self-assembly of cyclophilin hCyp-18 ligands through oxorhenium coordination

The dynamic combinatorial assembly of independent modules A and B through oxorhenium(V) coordination by a NS2+S motif in the presence of cyclophilin hCyp-18-an important peptidyl-prolyl isomerase-was investigated. Increasing glutathione (GSH) concentrations were used to dissociate [ARe(V)OB] complexes that displayed low affinity for hCyp-18. Conversely, coordinates that displayed submicromolar affinities for hCyp-18 were protected against thiol exchange and could be detected by LC-MS. Determination of the GSH concentration that decreased the extracted ionic current of the complex by 50 % (CC(50)) enabled the selection of three oxorhenium coordinates that were shown to bind to the active site of hCyp-18 and to inhibit its peptidyl-prolyl isomerase activity in the micromolar to submicromolar range.