This review summarizes the results from the INRA (Institut National de la Recherche Agronomique) divergent selection experiment on residual feed intake (RFI) in growing Large White pigs during nine generations of selection. It discusses the remaining challenges and perspectives for the improvement of feed efficiency in growing pigs. The impacts on growing pigs raised under standard conditions and in alternative situations such as heat stress, inflammatory challenges or lactation have been studied. After nine generations of selection, the divergent selection for RFI led to highly significant (P<0.001) line differences for RFI (−165 g/day in the low RFI (LRFI) line compared with high RFI line) and daily feed intake (−270 g/day). Low responses were observed on growth rate (−12.8 g/day, P<0.05) and body composition (+0.9 mm backfat thickness, P=0.57; −2.64% lean meat content, P<0.001) with a marked response on feed conversion ratio (−0.32 kg feed/kg gain, P<0.001). Reduced ultimate pH and increased lightness of the meat (P<0.001) were observed in LRFI pigs with minor impact on the sensory quality of the meat. These changes in meat quality were associated with changes of the muscular energy metabolism. Reduced maintenance energy requirements (−10% after five generations of selection) and activity (−21% of time standing after six generations of selection) of LRFI pigs greatly contributed to the gain in energy efficiency. However, the impact of selection for RFI on the protein metabolism of the pig remains unclear. Digestibility of energy and nutrients was not affected by selection, neither for pigs fed conventional diets nor for pigs fed high-fibre diets. A significant improvement of digestive efficiency could likely be achieved by selecting pigs on fibre diets. No convincing genetic or blood biomarker has been identified for explaining the differences in RFI, suggesting that pigs have various ways to achieve an efficient use of feed. No deleterious impact of the selection on the sow reproduction performance was observed. The resource allocation theory states that low RFI may reduce the ability to cope with stressors, via the reduction of a buffer compartment dedicated to responses to stress. None of the experiments focussed on the response of pigs to stress or challenges could confirm this theory. Understanding the relationships between RFI and responses to stress and energy demanding processes, as such immunity and lactation, remains a major challenge for a better understanding of the underlying biological mechanisms of the trait and to reconcile the experimental results with the resource allocation theory.

Inflammation mediates several chronic diseases. Micronutrients can act on inflammation, either through modulating cytokine production or by scavenging by-products of activated white cells. Identifying dietary patterns (DP) reflecting these mechanisms and relating them to inflammation is of interest. The objective of the study was to identify DP specifically associated with intakes of nutrients potentially involved in inflammatory processes in a middle-aged population and investigate long-term associations between these DP and C-reactive protein (CRP) status assessed several years later. Subjects included in the Supplementation in Vitamins and Mineral Antioxidants 2 cohort study, having available data on dietary assessment carried out in 1994–5 and CRP measurement in 2007–9, were included in the analysis. DP were extracted with reduced rank regression (RRR), using antioxidant micronutrients and PUFA as response variables. Associations between CRP measurements >3 mg/l and extracted DP were then examined with logistic regression models providing OR and 95 % CI. A total of 2031 subjects (53·2 % women, mean follow-up duration: 12·5 years) were included in the analyses. Of the four extracted DP, a DP with high loading values of vegetables and vegetable oils, leading to high intakes of antioxidant micronutrients and essential fatty acids, was significantly and negatively associated with risk of elevated CRP (OR 0·88; 95 % CI 0·78, 0·98). Conversely, a DP reflecting a high n-6:n-3 fatty acid intake ratio was positively and significantly associated with elevated CRP (adjusted OR 1·15; 95 % CI 1·00, 1·32). DP extracted with RRR provide support for further exploration of relationships between dietary behaviour and inflammation.

Since decades, production traits such as growth rate, feed efficiency or body composition have been drastically increased in pigs by genetic selection. Whether this selection impacted animal robustness is still unclear. In this study, we compared Large White (LW) pigs, a breed submitted to intense genetic selection for production traits, and Basque (B) pigs, a local rustic breed, reared in two different housing environments (conventional v. enriched). Adaptation to housing conditions among each breed was evaluated at the level of endocrine and immune traits. These are known to be impacted by housing conditions and breed; however, the interaction effects between genotype and environment are less described. Animals (20 per breed and housing environment) entered the experiment at 35 kg of live weight. Levels of cortisol, acute-phase inflammatory proteins, immunoglobulins and hydrogen peroxide, blood formula, lymphocyte proliferation and in-vitro cytokine expression were measured at ∼115 kg of live weight. Animals were checked for skin injuries during the growing period. At slaughter, at the average live weight of 145 kg, carcasses were examined for pathological conditions of the respiratory tract. The major result was that the two breeds exhibited differences in response to the housing environment. Among the 24 sanitary, endocrine or immune traits investigated, the housing conditions affected eight variables in both breeds (salivary cortisol at 0700 and 1900 h, severity of pneumonia at slaughter) or only in B pigs (severe skin lesions) or LW pigs (salivary cortisol at 1500 h, granulocyte numbers and lymphocyte/granulocyte ratio and lymphocyte proliferation). These observations strengthen the hypothesis that selection for high meat production level might be associated with an increased susceptibility of animals to environmental stressors.

In the spirit of the theoretical evolution from the Helmholtz model to the Gouy–Chapman–Stern model for electric double-layer capacitors, we explored the effect of a diffuse layer on the capacitance of mesoporous carbon supercapacitors by solving the Poisson–Boltzmann (PB) equation in mesopores of diameters from 2 to 20 nm. To evaluate the effect of pore shape, both slit and cylindrical pores were considered. We found that the diffuse layer does not affect the capacitance significantly. For slit pores, the area-normalized capacitance is nearly independent of pore size, which is not experimentally observed for template carbons. In comparison, for cylindrical pores, PB simulations produce a trend of slightly increasing area-normalized capacitance with pore size, similar to that depicted by the electric double-cylinder capacitor model proposed earlier. These results indicate that it is appropriate to approximate the pore shape of mesoporous carbons as being cylindrical and the electric double-cylinder capacitor model should be used for mesoporous carbons as a replacement of the traditional Helmholtz model.

Capacitive energy storage mechanisms in nanoporous carbon supercapacitors hinge on endohedral interactions in carbon materials with macro-, meso-, and micropores that have negative surface curvature. In this article, we show that because of the positive curvature found in zero-dimensional carbon onions or one-dimensional carbon nanotube arrays, exohedral interactions cause the normalized capacitance to increase with decreasing particle size or tube diameter, in sharp contrast to the behavior of nanoporous carbon materials. This finding is in good agreement with the trend of recent experimental data. Our analysis suggests that electrical energy storage can be improved by exploiting the highly curved surfaces of carbon nanotube arrays with diameters on the order of 1 nm.

In the past two decades, the fact that “small is different” has been established for a wide variety of phenomena, including electrical, optical, magnetic, and mechanical behavior of materials. However, one largely untapped but potentially very important area of nanoscience involves the interplay of electricity and mechanics at the nanoscale. In this article, predicated on both phenomenological approaches and atomistic calculations, we summarize the state-of-the-art in understanding electromechanical coupling at the nanoscale. First, we address flexoelectricity—the coupling of strain gradient to polarization. Flexoelectricity exists in both piezoelectric and nonpiezoelectric dielectrics. As a high-order spatial-dispersion effect, the flexoelectricity becomes more and more important with the reduction of the spatial scale of the problem. Exploitation of this phenomenon and the associated nanoscale size effects can lead to tantalizing applications, such as “piezoelectric nanocomposites without using piezoelectric materials.” The second issue concerns electromechanical effects at the dielectric/metal interface. An interface in solids typically exhibits a lower symmetry compared to that of the associated adhering materials. This symmetry reduction can drastically affect the electromechanical and dielectric behavior of the material at the nanoscale.

Metal clusters supported by transition metal oxides, as exemplified by the Au/TiO2 system, have found broad applications as catalytic and sensor materials. The unusual properties of these systems originate from the specific interactions of metal clusters mediated by an oxide substrate, including local reduction below the cluster. In this work, we present recent results on the local interactions between one-dimensional defects on a TiO2 surface and their reactivity with oxygen and Au nano-clusters studied by a combination of Scanning Tunneling Microscopy and Spectroscopy (STM/S). High-resolution STM images, interpreted with first-principles theory, show that the observed one-dimensional strands have partially reduced Ti atoms coordinated above three-coordinated, surface oxygen atoms. When strands are exposed to 5 x 10-7 Torr O2 at 300 K, oxygen is adsorbed and randomly nucleated on and along the strands. The results indicate the presence of exposed Ti that act as an active site for oxygen adsorption even at room temperature. Gold nano-particles of diameters 5 nm and less have also been deposited on the sub-stoichiometric rows of TiOx and characterized by STM. Like point defects and step edges on TiO2(110), the strands serve as nucleation sites for gold nano-clusters. The 1D defects of the surface are interpreted in terms of a surface crystallographic shear type structure, in contrast to the proposed Ti2O3 added row model by Onish and Iwasawa [Phys. Rev. Lett. 76, (1996) 791]. The implications of this behavior and specific interaction between gold clusters, defects and gas molecules for catalytic activity of the Au/TiO2 system are discussed.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Experimental techniques for SPM imaging and spectroscopy of low-dimensional systems have significantly progressed in recent years. At the same time, new simulation methods and computational techniques have allowed the development of a theoretical basis to the interpretation and understanding of the measurements. In this contribution, we concisely review two state-of-the-art modeling methods for scanning probe microscopy, as applied to carbon nanostructures.

The I-V characteristics of small Sin clusters and short C20 chains between atomistic Al leads were calculated using a new ab initio transport code based on a nonequilibrium Greens function formalism. All of the Si diaplay metallic I-V characteristics with typical conductances ranging between tow and three (units Go = 2e2/h). The transport properties of these molecular devices may be understood in terms of both the bandstructure ofelectrodes, and the molecular levels of the clusters as modified by the lead environment. Turning to the short C20 chains, these behave as short C20 chains, these behave as short nanowires whose tranmission depends sensitively on the orientation and distance between the individual C20 molecules. Transport through the molecular chains is accompained by a significant amount of charge transfer, which however remains localized at the electrode/molecular interface.

Our simulations predict that boron-nitride (BN) doping in carbon nanotubes can greatly improve the field emission properties of these systems. The intrinsic electric field associated with the polarity of the B-N bond enhances the emitted current density through a reduction of the work function at the tip. Using a combination of real-space and plane-wave ab initio methods, we show that this effect is present in both coaxial (BN@C) and linear (BN/C) nanotubular assemblies. While in the coaxial geometry the improvement amounts to a factor of five, the current density is predicted to increase by up to two orders of magnitude in BN/C superlattices.

Carbon nanotube systems can substantially increase their capacity for Li ion uptake, provided that the nanotube interiors become accessible to the ions. We examine theoretically, with ab initio simulations, the ability of Li ions to enter a nanotube interior. While our calculations show that it is quite unlikely for the ions to pass through pristine nanotubes, they are much more likely to enter via large-sized topological defects consisting of at least 9- or more membered rings. It is unlikely that such defects are formed spontaneously, but it may be possible to induce such topological defects by violent non-equilibrium means such as ball milling, chemical means and/or ion bombardment. Indeed, recent experiments on ball milled nanotube samples do report an important increase in the Li ion uptake.

Young animals learn feeding through trial and error processes and from social models, especially the parental one (i.e. Suboski and Bartshumas, 1984). Under practical conditions the mother-young bond has been reduced by early weaning in piglets or deleted in artificially hatched chicks. In both cases feeding experiences develop in groups of congeners of the same age. Negative reinforcements of feeding experiences have been demonstrated with diets containing concanavalin A from jackbean seeds (Canavalia ensiformis) (Leon et al., 1991). Preliminary trials suggested that piglets react similarly to jackbean containing diets. The aim of the present experiment was to investigate the capacity of piglets and chicks to influence the feeding behaviour of conspecifics according to their previous feeding experience (negative with concanavalin A, or neutral) and their social reactivity.