Contribution of partially labile complexes to the DGT metal flux

Penetration of complexes into the resin layer can dramatically increase the contribution of complexes to the metal flux measured with a DGT (diffusive gradients in thin films) sensor, but equations to describe this phenomenon were not available. Here, simple approximate analytical expressions for the metal flux, the lability degree and the concentration profiles in a DGT experiment are reported. Together with the thickness of the reaction layer in the gel domain, the effective penetration distance into the resin layer that would be necessary for full dissociation of the complex (λ(ML)) plays a key role in determining the metal flux. An increase in the resin-layer thickness (r) effectively increases the metal flux and the lability degree until r ≈ 3λ(ML). For the usual DGT configuration, where the thickness of the gel layer exceeds that of the resin layer, the complex is labile if r > (D(ML)/k(d))?, where D(ML) is the diffusion coefficient of the metal complex and k(d) its dissociation rate constant. A general procedure for estimating the lability of any complex in a standard DGT configuration is provided.     

Rate dependence of the reaction mechanism in olivine NaFePO4 Na‐ion cathode material

When electrode materials are driven away from equilibrium conditions, significant differences occur in their (dis)charge mechanism. In this paper, the changes in the phase transformations of the olivine NaFePO₄ are examined as a function of the cycling rate from the thorough analyses of both the voltage‐composition profiles of galvanostatic cycling, and operando laboratory and synchrotron X‐ray diffraction experiments. While the charge mechanism remains unchanged at all C‐rates, high cycling rates enable to unveil 2 concomitant biphasic reactions appearing as a 3‐phase state at lower rates. This finding allows rationalising the asymmetries observed at low rates, which are rooted in different reaction kinetics.     

5-Hydroxymethylfurfural content in foodstuffs determined by micellar electrokinetic chromatography

Micellar electrokinetic chromatography (MEKC) has been applied for the determination of 5-hydroxymethylfurfural in several foodstuffs. A 75 mM phosphate buffer solution at pH 8.0 containing 100 mM sodium dodecylsulphate was used as background electrolyte (BGE), and the separation was performed by applying +25 kV in a 50 μm I.D. uncoated fused-silica capillary. Good linearity over the range 2.5–250 mg kg⁻¹ (r² ? 0.999) and run-to-run and day-to-day precisions at low and medium concentration levels were obtained. Sample limit of detection (0.7 mg kg⁻¹) and limit of quantification (2.5 mg kg⁻¹) were established by preparing the standards in blank matrix. The procedure was validated by comparing the results with those obtained with liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). Levels of HMF in 45 different foodstuffs such as breakfast cereals, toasts, honey, orange juice, apple juice, jam, coffee, chocolate and biscuits were determined.     

Hydropeaking effects on movement patterns of brown trout (Salmo trutta L.)

Radiotelemetry was used to investigate seasonal movement and home range of brown trout Salmo trutta (size range 188–420 mm fork length, N = 30) in two reaches of the Noguera Pallaresa River (Ebro Basin, north‐east Spain) subjected to different flow regulation schemes. NP‐1 reach is a bypassed section with near natural flow conditions, whereas the downstream reach NP‐2 is subjected to daily pulsed flow discharge (i.e., hydropeaking) from an upstream hydropower station. Significant differences in home range size (95% kernel estimates) and seasonal movement pattern between study reaches were found. Mean home range size was (μ ± SE) 112.1 ± 11.5 m in the bypassed reach NP‐1 and increased significantly in the hydropeaking reach NP‐2 up to 237.9 ± 37.2 m. There was a large individual variability in fish home range size within reaches. Most of the seasonal differences in fish movement among reaches were associated with the spawning season. Pulsed discharge events in NP‐2 during daytime in summer (lasting about 3 hr and increasing water flow from 1 to 20 m³/s) did not cause significant displacements in either upstream or downstream direction during the duration of the event. Our results highlight the importance of habitat connectivity in hydropeaking streams due to the need of brown trout to move large distances among complementary habitats, necessary to complete their life cycle, compared with unregulated or more stable streams.     

Offshoring Innovation to Emerging Countries: The Effects of IP Protection and Cultural Differences on Firms’ Decision to Augment Versus Exploit Home-Base-Knowledge

Developed-country multinationals (DMNEs) have increasingly engaged in the practice of offshoring innovation to emerging countries. In this article, we leverage and extend the institution-based view to further our understanding of this phenomenon. Specifically, we examine the differential effects of formal and informal institutions on DMNEs’ strategic decision to offshore innovation activities aimed at augmenting (versus exploiting) home-base-knowledge to emerging countries. Concerning formal institutions, we argue that the stronger the emerging host country’s IP protection, the higher the likelihood that a DMNE offshores innovation activities aimed at augmenting home-base-knowledge. Regarding informal institutions, we argue that the greater the cultural differences between the developed home country and the emerging host country, the higher the likelihood that a DMNE offshores innovation activities aimed at augmenting home-base-knowledge. Additionally, we propose a key contingency that attenuates the relationship involving IP protection while strengthening the one involving cultural differences: the DMNE’s experience with offshoring innovation. Analysis of 128 offshoring innovation implementations by 78 DMNEs in ten emerging countries provides support for all our hypotheses except for the one focused on the moderation effect of experience on the relationship involving cultural differences.     

Adjustable Hyperthermia Response of Self‐Assembled Ferromagnetic Fe‐MgO Core–Shell Nanoparticles by Tuning Dipole–Dipole Interactions

The Fe‐MgO core‐shell morphology is proposed within the single‐domain nanoparticle regime as an enhanced magnetically driven hyperthermia carrier. The combinatory use of metallic iron as a core material together with the increased particle size (37–65 nm) triggers the tuning of dipolar interactions between particles and allows for further enhancement of their collective heating efficiency via concentration control. A theoretical universal estimation of hysteresis losses reveals the role of dipolar interactions on heating efficiency and outlines the strong influence of coupling effects on hyperthermia opening a novel roadmap towards multifunctional heat‐triggered theranostics particles.     

Biogas production in low-cost household digesters at the Peruvian Andes

Low-cost tubular digesters originally developed in tropical regions have been adapted to the extreme weather conditions of the Andean Plateau (3000-4000 m.a.s.l.). The aim of this study was to characterise biogas production in household digesters located at high altitude, operating under psychrophilic conditions. To this end, two pilot digesters were monitored and field campaigns were carried out in two representative digesters of rural communities. Digesters’ useful volume ranged between 2.4 and 7.5 m³, and hydraulic residence time (HRT) between 60 and 90 days. The temperature inside the digester’s greenhouse ranged between 20 and 25 °C. Treating cow manure, a specific biogas production around 0.35 m³ kg_VS⁻¹ was obtained, with some 65% CH₄ in biogas. In order to fulfil daily requirements for cooking and lighting, biogas production should be enhanced without increasing implementation costs as not to impede the expansion of this technology at household scale. In this sense, HRT below 60 days and OLR above 1 kg_VS m⁻³ day⁻¹ should be investigated to decrease digesters’ volume (i.e. costs) and increase biogas production rate. The adaptation of conventional gas burners to biogas characteristics can also contribute in improving the efficiency of the system.     

Bidirectional power flow control of a power converter using passive Hamiltonian techniques

A controller able to achieve bidirectional power flow for a boost‐like full‐bridge rectifier is presented. It is shown that no single output yields a stable zero dynamics for power flowing both ways. The controller is computed using port Hamiltonian passivity techniques for a suitable generalized state space averaging truncation of the system, which transforms the control objectives, namely specified output mean value of the voltage dc‐bus and unity input power factor in the ac side, into a regulation problem. Simulation and experimental results for the full system confirm the correctness of the simplifications introduced to obtain the controller. Copyright © 2007 John Wiley & Sons, Ltd.     

Metal flux and dynamic speciation at (bio)interfaces. Part IV: MHEDYN, a general code for metal flux computation; application to particulate complexants and their mixtures with the other natural ligands

Metal flux at consuming interfaces (e.g., sensors or microorganisms) is simulated in environmental multiligand systems using a new numerical code, MHEDYN (Multispecies HEterogeneous DYNamics), based on the lattice Boltzmann method. The attention is focused on the computation of the maximum flux (i.e.,the flux controlled by diffusion-reaction in solution) of Cu(II). Part III described flux computation in the presence of simple ligands and fulvic/humic substances. This paper (Part IV) discusses the case of metal complexes formed with aggregates including a broad range of sizes and diffusion coefficients and their mixture with simple and fulvic ligands under typical natural water conditions. This paper describes the dynamic contribution of the various size classes of aggregate Cu(II) complexes for the first time. In two typical waters containing mixtures of ligands, the contribution of aggregates is found to be small, whereas that of fulvics may play a major role, even under pH conditions where the lability of their Cu(II) complexes is low. These results point out the great usefulness of MHEDYN for dynamic speciation in very complex mixtures. In all cases, MHEDYN enables us to compute the concentration profile of each complex and itstime evolution, as well as the steady-state flux and the corresponding contribution of each complex to the flux. Thus, MHEDYN should be very useful for comparing theoretical predictions with experimental measurements of metal bioavailability or of dynamic sensor response in a complete aquatic medium.     

A system to understand hand-drawn floor plans using subgraph isomorphism and Hough transform

Presently, man-machine interface development is a widespread research activity. A system to understand hand drawn architectural drawings in a CAD environment is presented in this paper. To understand a document, we have to identify its building elements and their structural properties. An attributed graph structure is chosen as a symbolic representation of the input document and the patterns to recognize in it. An inexact subgraph isomorphism procedure using relaxation labeling techniques is performed. In this paper we focus on how to speed up the matching. There is a building element, the walls, characterized by a hatching pattern. Using a straight line Hough transform (SLHT)-based method, we recognize this pattern, characterized by parallel straight lines, and remove from the input graph the edges belonging to this pattern. The isomorphism is then applied to the remainder of the input graph. When all the building elements have been recognized, the document is redrawn, correcting the inaccurate strokes obtained from a hand-drawn input. Received 6 June 1996 / Accepted 4 February 1997