Automating a 96-Well Microtiter Plate Assay for Quick Analysis of Chemically Available Lysine in Foods

A new method for quick analysis of available lysine content in different food products has been developed by automating a 96-well microtiter plate assay. Although manual fluorometric methods validated in order to determinate available lysine content already existed for this compound, the benefits of applying appropriate automation should provide continuous operation, increased precision, an affordable electronic audit trail, and significantly reduced time and reagent consumption. The objective of this work was to adapt the ortho-phthaldialdehyde (OPA) fluorometric method to an automated workstation. Considerable effort went into developing and validating an automated method. The analytical parameters of linearity (r?=?0.999), the precision of the method (relative standard deviations?=?2.8–3.0 % for the different samples), and the results of the comparison with the corresponding OPA manual fluorometric method show that the studied method is useful for the measurement of available lysine in several food products from different natural origins such as liquid foods (soy, oat, quinoa beverages, and ultra-high temperature/sterilized milk) and powdered samples (powdered adapted, powdered follow-up, and junior milk infant formulas) with reduced time and reagent consumption.     

One‐Pot Synthesis of Functional Helicoidal Hybrid Organic–Inorganic Nanofibers with Periodically Organized Mesoporosity

The one‐pot synthesis and properties of multifunctional hybrid mesoporous organosilica fibers with helical shapes are described. These hybrid mesoporous fibers are prepared without chiral elements and functionalized with a large variety of organic R functions (R = alkylthiols, phenylsulfonates, alkylphosphonates, dansyl, aminopropyl, fluoroalkyl, etc.). The resulting nanomaterials are thoroughly characterized by a variety of techniques. The use of a synergetic combination of achiral molecules as co‐directing structuring agents, a surfactant, and an organofunctional silica precursor R‐Si(OR)₃ allows, via carefully tuning of the main synthesis parameters and processing conditions, to control the shape, which is the anisotropic factor, of the hybrid nanofibers. The functionalization of the hybrid materials with fluorescent molecules (dansyl) and gold nanoparticles opens possibilities for sensor and catalytic applications, respectively. Moreover, these hybrid nanofibers can be easily transferred in organic solvents or in a “green” solvent such as water to make stable colloidal dispersions. This tunable functionality of nanofibers also allows their transferability into a variety of polymeric hosts (PVDF, PVBu, and PVP) allowing the formation of functional homogeneous nanocomposite hybrid membranes.     

Mechanochemical degradation of poly(vinyl fluoride) by sodium hydroxide measured by microindentation

The degradation of the mechanical properties of deformed PVDF during its mechanochemical ageing in sodium hydroxide (soda) was followed by microindentation measurements, especially the local reduction of the elastic modulus and the hardness. This allows measurements on a local scale of the mechanical properties on the surface and in-depth as a function of the strain level and the ageing time. Microindentation tests with Berkovich indenter have been performed with a Nanoindenter XP^® (MTS). Measurements are made at penetration depth less than 2 μm for an applied load of 10 mN. During ageing in soda (Ph 14) at 90 °C up to 16 days, various deformations ε (0, 22 and 38%) are imposed on PVDF tensile specimen. For the first two imposed deformations (ε = 0 and ε = 22%), mechanical degradation is limited to some percent (less than 7%). For the greatest deformation (ε = 38%), mechanical degradation continues to decrease with ageing time (more than 21%). Microindentation tests show that a range of low deformations exists in which the mechanochemical degradation is limited and no limitation is observed for larger imposed deformation.     

Antimicrobial and antibiofilm activities of procyanidins extracted from laurel wood against a selection of foodborne microorganisms

This study aimed to evaluate the antimicrobial and antibiofilm activities of two procyanidins isolated from an ethyl acetate extract of laurel wood against a selection of foodborne pathogens. The analysis of the extract by HPLC–DAD/ESI–MS allowed us to detect the presence of two procyanidins, which were selectively isolated and identified by chromatographic and spectroscopic means as cinnamtannin B‐1 ( 1 ) and procyanidin B‐2 ( 2 ). Procyanidins 1 and 2 exhibited two biological activities: inhibition of bacterial growth at high concentrations and prevention of biofilm formation at lower concentrations. Synergistic effect was also detected when both compounds were tested in combination against Listeria monocytogenes. Significant effects were also detected on disruption of preformed biofilm. The ability of procyanidins to inhibit microbial growth and biofilm formation and to synergistically work with each other may stimulate a market as natural food preservatives, and/or natural sanitisers for processing equipment where foodborne pathogens reside.     

Integration of GPU Computing in a Software Radio Environment

This article studies the integration of Graphics Processing Units in a Software Defined Radio environment. Two main solutions are considered, based on two levels of granularity for the parallelization. First, a fine grain parallelism solution, which is an extension of the existing solutions but adapted to operations of large computational complexity, is proposed. Second, an original solution based on coarse grain approach allowing better usage of the computing resources and easier parallelism extraction is described. For both solutions, scheduling and communication design as well as implementation are given, along with integration in the environment. Both solutions have been implemented and compared on different operations types and on multi-operations sequences. It is clearly shown that using the second solution can provide performance improvement, while the first one is not adapted to SDR applications.