Effect of chemical treatments of sugar beet fibre on their physico-chemical properties and on their in-vitro fermentation

Chemically treated and dried sugar beet fibres were fermented in vitro in order to study the effects of chemical and physico-chemical parameters of dietary fibre on their colonic fermentation. Sugar beet fibre was treated with dilute alkali, removing mainly acetyl and methyl ester groups, and/or with dilute acids eliminating arabinose, galactose and certain uronic acid residues. The chemical treatments led to an increase in the hydration properties and fermentability by improvement of the accessibility of the remaining polysaccharides. However, if the chemically treated fibres were dried under harsh conditions (100°C), their hydration properties and their fermentability were limited, probably because of structural collapse of the fibre matrix. Whatever the conditions for chemical treatments and drying of the sugar beet fibres, it was possible to predict their fermentability from the water-binding capacity. Because of the relationship between the physiological effects of dietary fibres and the extent to which they are fermented, this result underlines the importance of the physico-chemical characterisation of the fibre in order to acquire a better knowledge of their physiological effects.     

Consumer perceptions: pork and pig production. Insights from France, England, Sweden and Denmark

Consumer focus groups in France, England, Sweden and Denmark were used to obtain insights into the decision-making involved in the choice of fresh pork and attitudes towards today's pig production systems. Many positive perceptions of pork meat were evoked. Negative images of the production systems in use today were expressed, but rationalised in terms of consumer demands, market competition and by comparisons to previous systems of production. Knowledge of production systems appeared of little consequence in terms of any meat market potential as several groups freely remarked that there was no link between the negative images of production methods and their purchase behaviour. The groups were clearly confused and mistrusted the limited information available at the point of purchase. Careful consideration should be given to meat labelling, in particular taking account of the evident consumer ethnocentrism, to assure that such information is targeted to enhance consumer confidence.     

Exposure assessment of the Belgian population to pesticide residues through fruit and vegetable consumption

Exposure of the Belgian consumer to pesticide residues from the consumption of fruit and vegetables was determined based on data collected in the Belgian food consumption survey performed by the Scientific Institute for Public Health and data from the Belgian Federal Agency for the Safety of the Food Chain 2005 monitoring programme. A first screening of pesticide residue exposure was performed by a deterministic approach. For most pesticide residues studied, the exposure was 100 times lower than the acceptable daily intake (ADI). However, for a high consumer (97.5th percentile of consumption) the intake could reach 23% of the ADI for imazalil, 15% for chlorpropham, 14% for the dithiocarbamates, 10% for dimethoate and lambda-cyhalothrin, and 9% for chlorpyriphos. Nevertheless, probabilistic exposure assessment performed on these pesticides in a second phase of the study indicated that, except for chlorpropham, the probability to exceed the ADI is much lower than 0.1%.     

Long-term dietary exposure to lead of the population of Jiangsu Province, China

Deterministic and probabilistic estimates of the chronic exposure to lead (Pb) for the inhabitants in Jiangsu Province, China, were performed. Pb contamination data were obtained from the national food contamination monitoring programme during 2001-2006 and 2600 samples from 38 commodities in Jiangsu were included. Food consumption data were from the national diet and nutrition survey conducted in 2002, including 3879 subjects aged 2-80 years and 185 children aged 2-6 years in Jiangsu. Contributions from 38 commodities were included in the calculations. Using the provisional tolerable weekly intakes (PTWI) divided into daily intakes (PTWI(d)) of 3.57 microg kg(-1) bw day(-1) in the risk assessment, exposures calculated by the deterministic approach for children and the general population were 77% and 43% of the PTWI(d), respectively, which were nearly similar to the mean intake calculation in the probabilistic approach. The percentage of people whose exposure level exceeded the PTWI(d) for children, the general population, urban population and rural population were 16%, 0.4%, 0.1%, and 0.5%, respectively. The 50th, 95th and 99th percentiles of Pb exposure for children were 2.6, 4.4 and 5.5 microg kg(-1) bw day(-1), respectively. Rice followed by wheat flour and bean products contributed most to the total Pb intake for both children and the general population. This study indicated that the Pb dietary exposure in Jiangsu Province, especially for children, would be a public health concern.     

Micromixers to produce cosmetic emulsions

In the cosmetics industry, emulsions play a key-role in active solubilization and texture/efficacy optimization. However, depending on their physico-chemical properties, the active ingredients are often more stable in a single phase: for example, Vitamin A is more stable in an oily phase than in a water phase. We have developed a special mixing device which produces an emulsion in the body of the pump, immediately before application on the skin. The mixing unit consists of two silicon chips. Each chip has several Y-shaped microchannels and intersections etched on its upper surface. When the two etched surfaces are bonded together, they produce series of interconnecting micromixing elements which permit the repeat mixing of the two phases, thus producing an extremely homogenous emulsion. These micromixers require carefully designed formulae in which the physico-chemical properties of each raw material are essential to obtain a spontaneous emulsion. This device has been incorporated into a spray pack and optimized to deliver the spontaneous emulsion when finger pressure is applied.     

Modal analysis and suppression of the Fourier modal method instabilities in highly conductive gratings

The Fourier modal method (FMM), often also referred to as rigorous coupled-wave analysis (RCWA), is known to suffer from numerical instabilities when applied to low-loss metallic gratings under TM incidence. This problem has so far been attributed to the imperfect conditioning of the matrices to be diagonalized. The present analysis based on a modal vision reveals that the so-called instabilities are true features of the solution of the mathematical problem of a binary metal grating dealt with by truncated Fourier representation of Maxwell's equations. The extreme sensitivity of this solution to the optogeometrical parameters is the result of the excitation, propagation, coupling, interference, and resonance of a finite number of very slow propagating spurious modes. An astute management of these modes permits a complete and safe removal of the numerical instabilities at the price of an arbitrarily small and controllable reduction in accuracy as compared with the referenced true-mode method.     

Large scale synthesis of single-crystal and polycrystalline boron nitride nanosheets

Boron nitride nanosheets (BNNSs) have an identical crystal structure and similar lattice parameter to those of graphene sheets. However, growing quality BNNSs consisting of only several atomic layers remains a challenge. Here, we report on the synthesis of BNNSs at a temperature of 350 °C using a CO₂ pulsed laser plasma deposition (CO₂-PLD) technique by irradiating a pyrolytic hexagonal boron nitride (h-BN) target. The deposition was performed either in vacuum at a pressure of 0.2 Pa, for which we obtained polycrystalline BN, or in hydrogen (H₂) atmosphere at a pressure of 26 Pa for which we obtained single-crystal BNNSs. The presence of H₂ seems to minimize the side effects of sputtering and the material shows higher purity and better crystallinity. High resolution transmission electron microscopy (HRTEM) showed the sheets to be mostly defect-free and to have the characteristic honeycomb structure of six-membered B₃-N₃ hexagon. HRTEM, electron diffraction, X-ray diffraction, Raman scattering, and Fourier transform infrared spectroscopy clearly identified h-BN.     

WO3 nano-ribbons: their phase transformation from tungstite (WO3·H2O) to tungsten oxide (WO3)

Tungsten oxide (WO₃) nano-ribbons (NRs) were obtained by annealing tungstite (WO₃·H₂O) NRs. The latter was synthesized below room temperature using a simple, environmentally benign, and low cost aging treatment of precursors made by adding hydrochloric acid to diluted sodium tungstate solutions (Na₂WO₄·2H₂O). WO₃ generates significant interests and is being used in a growing variety of applications. It is therefore important to identify suitable methods of production and better understand its properties. The phase transformation was observed to be initiated between 200 and 300 ^°C, and the crystallographic structure of the NRs changed from orthorhombic WO₃·H₂O to monoclinic WO₃. It was rigorously studied by annealing a series of samples ex situ in ambient air up to 800 ^°C and characterizing them afterward. A temperature-dependent Raman spectroscopy study was performed on tungstite NRs between minus 180 and 700 ^°C. Also, in situ heating experiments in the transmission electron microscope allowed for the direct observation of the phase transformation. Powder X-ray diffraction, electron diffraction, electron energy-loss spectroscopy, and X-ray photoelectron spectroscopy were employed to characterize precisely this transformation.