Varietal and geographic classification of French red wines in terms of elements,amino acids and aromatic alcohols

Thirty-four French red wines from three regions already studied for their anthocyanin and flavonoid constituents have been further analysed for elements, amino acids and aromatic alcohols. An interpretation of the differences between wines related to their different geographic and varietal origins has been made from the results of statistical analyses: F statistic, principal component analysis (PCA) and stepwise discriminant analysis (SDA). Wine samples produced near Bordeaux were found to be characterised by higher rubidium and lower lithium and calcium concentrations. Differences between wine samples made from the same grape variety or produced in the same region are mainly related to differences in potassium and ash contents. The PCA demonstrates that the concentration of most amino acids in wines is mainly a function of the technology used in wine production. Moreover, it shows that the concentration of proline, hydroxyproline and ethanolamine are generally lower in wines prepared from Carignan, Cinsault and Grenache grapes than in wines from Cabernet Franc, Cabernet Sauvignon or Merlot grapes. Finally, it shows clear differences between wines according to the latitude of the production centre. These differences correspond to increasing total nitrogen content from south to north, ie Narbonne and Bordeaux versus Angers. In discriminant analysis Bordeaux wines were characterised by high rubidium and low arginine concentrations, Angers wines by a lower arginine content and Narbonne wines by their abundance of magnesium and deficiency of ethanolamine.     

Relation between volumetric changes of unsaturated polyester resin and surface finish quality of fiberglass/unsaturated polyester composite panels

Resin dimensional changes, including cure shrinkage and thermal expansion, highly influence the surface finish quality of composite parts. Low profile additives (LPA) are commonly incorporated in unsaturated polyester (UP) resins to compensate for resin shrinkage and obtain a high quality surface finish. In this study, the dimensional change of an UP resin with different LPA contents was characterized. Both resin cure shrinkage and resin thermal expansion were measured. A simple methodology was then developed to estimate the surface finish quality of panels, manufactured by resin transfer molding (RTM), based on the prediction of part thickness variation during the process. Results show good agreement with the experimental investigations. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Cure shrinkage characterization of an epoxy resin system by two in situ measurement methods

Dimensional accuracy of composites manufacturing is a major issue for part producers, especially when tight tolerances are required. One of the main causes of dimensional variations is the resin volumetric changes during the cure. In this article, volumetric cure shrinkage of a one part epoxy system was characterized using two different methods. First, a modified rheology method was used to measure the volumetric cure shrinkage after the gel point. Second, a gravimetric method measured the shrinkage over the entire cure. A linear relationship between the volumetric cure shrinkage and the degree‐of‐cure was deduced from the results and the resin cure kinetic models. Results show a good agreement between the two techniques. POLYM. COMPOS., 31:1603–1610, 2010. © 2009 Society of Plastics Engineers     

Simulation and evaluation of pilot-scale pulsed electric field (PEF) processing

Pulsed electric field (PEF) processing is a novel mild treatment for pumpable foods preservation at low or moderate temperatures. The electric field strength and the temperature distribution in the treatment chamber have been identified as the key processing parameters affecting the treatment efficacy and possibly the sensorial and nutritional quality of the food. A full 3D computational fluid dynamics (CFD) model of a pilot-scale PEF system with co-linear configuration of the electrodes was developed. The model couples the fluid dynamics and the electrical field and can be used to predict the liquid’s flow pattern, electric field distribution, temperature increase, and residence time in the treatment chamber. A total of 48 process conditions with different settings of applied voltage V, pulse length τ, pulse repetition rate (frequency) f and flow rate in combination with four different inlet temperatures were simulated for a model liquid food (NaCl solutions with two different electrical conductivities) and whole milk. The simulated PEF energy dissipated into the liquids was between 4 and 66 kJ/kg and process temperatures ranged from approximately 25 to 80 °C. The predicted temperature data agree well (R² > 0.99) with experimental measurements in five locations of the treatment chamber using fibre optic probes.     

Channel height dependent protein nucleation and crystal growth in microfluidic devices

We report on results of a study of protein crystallization in microfluidic devices with different channel heights. Multilayer soft lithography has been used for the fabrication of devices with integrated micro-valves and crystallization channels of height in the range from 15 μm to 180 μm. To demonstrate the channel height dependent nucleation and crystal growth, a standard batch crystallization solution composed of 60 mg/ml lysozyme, 100 mM acetate buffer pH 4.6 and 1.5 M NaCl was used with minimized sample quantity. Our results show that deep channels favorite the nucleation whereas shallow ones favorite the crystal growth. When the channel height is less than 50 μm the number of lysozyme crystals is dramatically reduced whereas their mean size is increased. Furthermore, our results also show the feasibility of decoupling nucleation and crystal growth in a stair-like channel which should facilitate the appearance of single crystals suitable for X-ray diffraction.     

Plasma impedance monitoring for real time endpoint detection of bulk materials etched in ICP tool

Plasma impedance monitoring (PIM) based on electrical measurements is successfully used as an alternative to determine real time detection endpoint during plasma etching of structured bulk materials. In this paper we present the results with this technique for the endpoint detection during the etching of various materials.The endpoint conditions are tested in the sixth harmonic components of the electrical plasma parameters with an RF sensor. The endpoint is determined when an electrical parameter transition is observed. This transition corresponds to the change of the total reactor impedance, and allows the etching of the doped layer to stop on the bulk substrate.Using a Smith chart we determine the best harmonics/electrical monitoring couple parameters for processes on various materials. Resistivity measurements are used before and after etching in order to confirm the usefulness of the PIM method.In this paper, we also demonstrate how to monitor a real time control of non-uniformity during the reactive ion etching (RIE) process in the case of gallium arsenide etching.     

An interaction stress analysis of nanoscale elastic asperity contacts

A new contact mechanics model is presented and experimentally examined at the nanoscale. The current work addresses the well-established field of contact mechanics, but at the nanoscale where interaction stresses seem to be effective. The new model combines the classic Hertz theory with the new interaction stress concept to provide the stress field in contact bodies with adhesion. Hence, it benefits from the simplicity of non-adhesive models, while offering the same applicability as more complicated models. In order to examine the model, a set of atomic force microscopy experiments were performed on substrates made from single-walled carbon nanotube buckypaper. The stress field in the substrate was obtained by superposition of the Hertzian stress field and the interaction stress field, and then compared to other contact models. Finally, the effect of indentation depth on the stress field was studied for the interaction model as well as for the Hertz, Derjaguin-Muller-Toporov, and Johnson-Kendall-Roberts models. Thus, the amount of error introduced by using the Hertz theory to model contacts with adhesion was found for different indentation depths. It was observed that in the absence of interaction stress data, the Hertz theory predictions led to smaller errors compared to other contact-with-adhesion models.     

Minimization of Copper Losses in Copper Smelting Slag During Electric Furnace Treatment

In the quest to achieve the highest metal recovery during the smelting of copper concentrates, this study has evaluated the minimum level of soluble copper in iron-silicate slags. The experimental work was performed under slag-cleaning conditions for different levels of Fe in the matte and for a range of Fe/SiO₂ ratios in the slag. All experiments were carried out under conditions where three phases were present (copper?Cmatte?Cslag), which is the condition typically prevailing in many slag-cleaning electric furnaces. The %Fe in the electric furnace matte was varied between 0.5?wt.% and 11?wt.%, and two different Fe/SiO₂ ratios in the slag were used (targeted values were 1.4 and 1.6). All experiments were performed at 1200°C. From thermodynamic considerations, from industrial experience, and from the results obtained in this study, the minimum soluble copper content in the electric furnace slag is expected to be near 0.55?wt.% Cu. This level does not account for a portion of the copper present as mechanically entrained matte/metal droplets. Taking this into account, the current authors believe an overall copper level in discard slag between 0.7?wt.% and 0.8?wt.% can be obtained with optimal operating conditions. For these conditions, the copper losses in the slag are roughly 75% as dissolved copper and 25% as entrained matte and copper. Such conditions include operating the electric furnace at metallic copper saturation, maintaining the %Fe in the electric furnace matte between 6?wt.% and 9?wt.%, not exceeding a slag temperature of 1250°C, and controlling the Fe/SiO₂ ratio in the smelting furnace slag at ??1.5. In addition, magnetite reduction needs to be performed efficiently during the slag-cleaning cycle so as to maintain a total magnetite content of ??7?wt.% in the discard slag. The authors further consider that under exceptionally well-controlled conditions, a copper content in electric furnace discard slag between 0.55?wt.% and 0.7?wt.% can be obtained, by minimizing entrained matte and copper solubility in the discard slag.     

Substrate-induced crystal plastic phase of a discotic liquid crystal

A new phase of a known discotic liquid crystal is observed at the interface with a rigid substrate. The structure of the substrate-induced phase has been characterized by atomic force microscopy, specular X-ray diffraction, and small-angle and wide-angle grazing incidence X-ray diffraction. The substrate-induced phase, which has a thickness of ～30 nm and a tetragonal symmetry, differs notably from the bulk phase. The occurrence of such phase casts a new light on alignment of discotic liquid crystals.     

Resonant laser-induced formation of double-walled carbon nanotubes from peapods under ambient conditions

The selective excitation of fullerenes encapsulated in single-walled carbon nanotubes (SWCNTs) is carried out by irradiating them using a UV laser, the wavelength of which corresponds exactly to their maximum of absorption. Under such conditions, fullerenes strongly absorb the laser energy, open, and break, while the containing SWCNT merely acts as both a nanoreactor and a mold which is only weakly heated by the laser. The containing tube confines the fullerene fragments, promotes their reconstruction into an inner tube, and protects them from air oxidation. This leads to the overall formation of double-walled carbon nanotubes (DWCNTs). The transformation is found to strongly depend on the laser irradiance and dose. This proves that the related mechanism is a multiphoton photolysis, different from the previous heat-induced transformation attempts found in the literature, whether the heat is produced by means of a thermostat, infrared laser, or nonresonant UV laser. The actual peapod-to-DWCNT transformation is monitored by Raman spectroscopy and high-resolution transmission electron microscopy.