Radiometric sensor for temperature control of food processing

This paper describes a novel planar antenna sensor created for the purpose of noninvasive temperature measurements using microwave radiometry. In order to improve radiometric measurements in industrial applications, a new generation of sensors is introduced, composed of a metallic sheet. Simulations based upon the method of moments is used both to design and to determine their electromagnetic performances. This paper also describes a radiometric device using these sensors to measure and control the temperature of food products during deep freezing processes. The results and discussions are presented.     

A literature review on MHE selection problem: levels,contexts, and approaches

This paper presents a review on selection problem of material handling equipment (MHE) and general equipment used in industry area. The issue on MHE is widely paid attention since MHE has contribution on material, good and product accomplishment. Few methods and softwares have been proposed and developed to select the most appropriate MHE for a complex selection problem. Today’s high diverisity of MHE categories and types influence the generation of many possible choices which leads to the complexity. In this paper, a further discussion in terms of MHE and equipment including three major points namely level of selection, the context of selection problem and the approaches are served to highlight the complex MHE selection according to the number of possible choices provided, to analyse the consideration for the problem context, and to reveal the superior method for complex MHE selection. Forty-two papers collected from the past study are presented asscociating each point of the discussion.     

A critical review on surface modifications mitigating dairy fouling

Thermal treatments performed in food processing industries generate fouling. This fouling deposit impairs heat transfer mechanism by creating a thermal resistance, thus leading to regular shutdown of the processes. Therefore, periodic and harsh cleaning-in-place (CIP) procedures are implemented. This CIP involves the use of chemicals and high amounts of water, thus increasing environmental burden. It has been estimated that 80% of production costs are owed to dairy fouling deposit. Since the 1970s, different types of surface modifications have been performed either to prevent fouling deposition (anti-fouling) or to facilitate removal (fouling-release). This review points out the impacts of surface modification on type A dairy fouling and on cleaning behaviors under batch and continuous flow conditions. Both types of anti-fouling and fouling-release coatings are reported as well as the different techniques used to modify stainless steel surface. Finally, methods for testing and characterising the effectiveness of coatings in mitigating dairy fouling are discussed.     

Adsorption de krypton sur Papyex dans le domaine de la monocouche

Among the different samples used for studying physisorbed films on graphitic surfaces, compressed exfoliated graphite, such as Papyex or Grafoil, plays an outstanding role, as it is particularly suitable for scattering experiments. But the compression performed to prepare this kind of sample has been shown to increase the heterogeneity of the surface, which results, as was observed in some cases [6,7,9] in an alteration of the shapes of isotherms, and a slowing down of the adsorption kinetics, with respect to more homogeneous graphitic surfaces.In this work, thermodynamical data characteristic for a physisorbed monolayer of krypton on Papyex have been determined from volumetric measurements performed either at constant temperature or at constant fractional coverage and compared to results obtained on more homogeneous surfaces.The isotherm set between 78 and 90 K is given in Figs. 2 and 3. It is on the whole compatible with the phase diagrams obtained on more homogeneous graphites (Fig. 1). But a slight smoothing of the steps, as well as a slowing down of the adsorption kinetics, which appears mainly for low temperatures and solid two-dimensional (2D) films, are observed as they were before [6, 7,9].Consistency between these results and those obtained by measurements at constant fractional coverage enables us to assume that adsorption equilibrium is reached in the temperature range common to both kinds of experiments.The constants A and B of the equation logP = −(A/T) + B, representing the dependence of the equilibrium pressure on temperature at constant fractional coverage, had been determined from volumetric measurement results, and also compared to values previously obtained in similar conditions on more homogeneous substrates, for different stages of the film formation (Table 1). Values for both types of samples are in good agreement, except for the 2D gas-solid transition (θ = 0.4 − T < 85 K), as could be foreseen from the shapes of isotherms in this domain, namely the bending of the linear part towards higher pressures than on more homogeneous graphitic substrates.The 2D triple point and critical temperatures with very similar values have been proposed before, which were determined in using graphite SPl type[10], while from other results it has been concluded that these two characteristic temperatures actually do not exist[11]. Owing to the lack of precision of our determinations the existence or the non existence of a 2D liquid domain cannot be asserted.As a conclusion, the main features of the krypton phase diagram being preserved, it can be assumed that the structural properties of the films determined on Papyex are, on the whole, characteristic of adsorption on a uniform surface.

Résumé

Les isothermes d'adsorption de krypton sur Papyex sont déterminées par volumétric dans le domaine de la monocouche, et pour des températures comprises entre 78 et 90, 2 K. Les données thermodynamiques que l'on peut déduire de ces courbes sont comparées à celles obtenues dans des conditions similaires sur des substrats graphitiques plus homogènes. Malgré quelques différences observées concernant la forme des isothermes et la cinétique de l'adsorption, les principales caractéristiques du diagramme de phase du film sont conservées.     

Synthesis and growth mechanism of ThO2–W–Mo alloy nanocomposite powder

Nanocomposite ultrafine powders of thorium oxide and tungsten molybdenum alloy were prepared by arcing between a pure molybdenum cathode and a thoriated tungsten anode under an argon–hydrogen atmosphere. The microstructure, morphology and chemical analyses of the ultrafine powders were examined by X-ray diffraction, transmission electron microscopy and associated techniques. The powders are composed of thorium oxide single-crystalline nano-grains decorated by tungsten molybdenum alloy particles which are crystallized in a metastable A15 structure. Two morphologies were observed: octahedra and needle-like particles. Every octahedral particle bigger than 15 nm had on each corner a metallic grain generally less than 8 nm in size. The needles had a length below 600 nm and their width to length ratio ranged from 1/3–1/15. They all presented on one of their ends a metallic particle which was comparable in size to the needle width. Other smaller particles (<10 nm) may be encountered along the edges. The metallic particles were found to be epitaxial on the thorium oxide grains according to the relation: (100) [011]_ThO2∥(100) [011]_A15. The extensive study of the microstructural and morphological properties of the powders leads us to suggest a growth mechanism of the nanocomposite particles. This revised version was published online in November 2006 with corrections to the Cover Date.     

Droplet transport by electrowetting: lets get rough!

Since the pioneering works of Wenzel and Cassie Baxter in the 1930s, and now with the trivialization of the micro- and nanotechnology facilities, superhydrophobic surfaces have been announced as potentially amazing components for applications such as fluidic, optical, electronic, or thermal devices. In this paper, we show that using superhydrophobic surfaces in digital microfluidic devices could solve some usual limitations or enhance their performances. Thus, we investigate a specific monophasic (air environment) microfluidic device based on electrowetting integrating either a hydrophobic or a superhydrophobic surface as a counter-electrode. The droplet transport using a superhydrophobic surface compared with a classical hydrophobic system led to some original results. Characterization of the dynamic contact angle and the droplet shape allows us to get new insight of the fluid dynamics. Among the remarkable properties reported, a 30 % lower applied voltage, a 30 % higher average speed with a maximum instantaneous speed of 460 mm/s have been measured. Furthermore, we have noticed a huge droplet deformation leading to an increase by a factor 5 of the Weber number (from 1.4 to 7.0) on SH compared to hydrophobic surfaces. Finally, we discuss some of the repercussions of this behaviour especially for microfluidic device.     

Reversible electrowetting on superhydrophobic silicon nanowires

This paper reports for the first time on the reversible electrowetting of liquid droplets in air and oil environments on superhydrophobic silicon nanowires (SiNWs). The silicon nanowires were grown on Si/SiO2 substrates using the vapor-liquid-solid (VLS) mechanism, electrically insulated using 300 nm SiO2, and hydrophobized by coating with a fluoropolymer C4F8. The resulting surfaces displayed liquid contact angle (Theta) around 160 degrees for a saline solution (100 mM KCl) in air with almost no hysteresis. Electrowetting induced a maximum reversible decrease of the contact angle of 23 degrees at 150 VTRMS in air.     

Functional Characterisation of ClpP Mutations Conferring Resistance to Acyldepsipeptide Antibiotics in Firmicutes

Acyldepsipeptide (ADEP) is an exploratory antibiotic with a novel mechanism of action. ClpP, the proteolytic core of the caseinolytic protease, is deregulated towards unrestrained proteolysis. Here, we report on the mechanism of ADEP resistance in Firmicutes. This bacterial phylum contains important pathogens that are relevant for potential ADEP therapy. For Staphylococcus aureus, Bacillus subtilis, enterococci and streptococci, spontaneous ADEP-resistant mutants were selected in vitro at a rate of 10⁻⁶. All isolates carried mutations in clpP. All mutated S. aureus ClpP proteins characterised in this study were functionally impaired; this increased our understanding of the mode of operation of ClpP. For molecular insights, crystal structures of S. aureus ClpP bound to ADEP4 were determined. Well-resolved N-terminal domains in the apo structure allow the pore-gating mechanism to be followed. The compilation of mutations presented here indicates residues relevant for ClpP function and suggests that ADEP resistance will occur at a lower rate during the infection process.     

Zipping effect on omniphobic surfaces for controlled deposition of minute amounts of fluid or colloids

When a drop sits on a highly liquid-repellent surface (super-hydrophobic or super-omniphobic) made of periodic micrometer-sized posts, its contact-line can recede with very weak mechanical retention providing that the liquid stays on top of the microsized posts. Occurring in both sliding and evaporation processes, the achievement of low-contact-angle hysteresis (low retention) is required for discrete microfluidic applications involving liquid motion or self-cleaning; however, careful examination shows that during receding, a minute amount of liquid is left on top of the posts lying at the receding edge of the drop. For the first time, the heterogeneities of these deposits along the drop-receding contact-line are underlined. Both nonvolatile liquid and particle-laden water are used to quantitatively characterize what rules the volume distribution of deposited liquid. The experiments suggest that the dynamics of the liquid de-pinning cascade is likely to select the volume left on a specific post, involving the pinch-off and detachment of a liquid bridge. In an applied prospective, this phenomenon dismisses such surfaces for self-cleaning purposes, but offers an original way to deposit controlled amounts of liquid and (bio)-particles at well-targeted locations.