Effect of temperature,pH and film thickness on nisin release from antimicrobial whey protein isolate edible films

BACKGROUND: An active packaging film based on whey protein isolate (WPI) was developed by incorporating nisin to promote microbial food safety. The effect of temperature and pH on the release of nisin from edible films of different thickness was investigated. The film mechanical properties and inhibitory effect were also evaluated. RESULTS: Nisin release was significantly favoured by low pH, with the highest release after 24 h (1325 IU), which was not significantly affected by temperature (5 or 10 °C). Thickness significantly affected film elongation, with thicker films showing the highest elongation (54.3 ± 2.7%). Water vapour permeability (0.15 ± 0.4 g mm m^?2 kPa^?1 h^?1) and elastic modulus were not significantly affected by thickness. The highest nisin effective diffusivity (5.88 × 10^?14 m² s^?1) was obtained using a solution at pH 4, 112 µm film thickness and a temperature of 5 °C. More than four log cycles of Brochotrix thermosphacta were reduced from the surface of a ham sample after 8 days of incubation at 4 °C by the active WPI film containing 473 IU cm^?2 nisin. CONCLUSION: Nisin diffusivity from WPI edible films was favoured at lower pH and film thickness. This active packaging film may be used to preserve the quality and safety of meat products. Copyright © 2009 Society of Chemical Industry     

Thermally grown vanadium oxide films and their electrical properties

A metal–insulator transition (MIT) occurring in vanadium oxide films prepared in different ways has been widely studied in many laboratories. It consists of a resistive change of various orders of magnitude taking place while traversing a temperature close to 67 °C. In this work the properties of VO_x films synthesized by thermal treatment of vanadium films which were vacuum-evaporated on an oxidized silicon substrate are shown. Such thermal oxidizing treatment was performed under atmospheric air at different temperatures during distinct times. Ellipsometry measurements allowed determining the thickness and optical constants of the layers after the oxidation process. From XRD, Raman and FTIR measurements, several phases with distinct oxygen content, V₂O₃, V₃O₅, VO₂ and V₂O₅, were found in the films, depending on the oxidation time and temperature. Current–temperature measurements across the films were carried out by using sandwich-type metal–insulator–metal structures. Unlike former studies on similar structures, no MIT was observed from these measurements. On the other hand, from room-temperature current–voltage measurements a well defined memristive behavior was found as a regular result in most of our structures. This memristive behavior is ascribed to the complex defect structure in the films, including the variable amount of oxygen vacancies in the lattice, rather than to the above-mentioned metal–insulator transition in vanadium oxide.     

Second Order Training and Sizing for the Multilayer Perceptron

Neural Processing Letters - An algorithm is developed for automated training of a multilayer perceptron with two nonlinear layers. The initial algorithm approximately minimizes validation error...     

Catalytic activity trends from pure Pd nanoclusters to M@PdPt (M = Co,Ni, and Cu) core-shell nanoclusters for the oxygen reduction reaction: A first-principles analysis

The trends of the catalytic activity toward the oxygen reaction reduction (ORR) from Pd₄₄ nanoclusters to M₆@Pd₃₀Pt₈ (M = Co, Ni, and Cu) core-shell nanoclusters was investigated using auxiliary density functional theory. The adsorption energies of O and OH were computed as predictors of the catalytic activity toward the ORR and the following tendency of the electrocatalytic activity was computed: Pt₄₄ ≈ M₆@Pd₃₀Pt₈ > M₆@Pd₃₈ > Pd₄₄. In addition, the adsorption of O₂ on the Ni₆@Pd₃₀Pt₈ and Pt₄₄ nanoclusters were investigated, finding an elongation of the O–O bond length when O₂ is adsorbed on the Ni₆@Pd₃₀Pt₈ and Pt₄₄ nanoclusters, suggesting that the O₂ is activated. Finally, the stabilities of the M₆@Pd₃₈ and M₆@Pd₃₀Pt₈ core-shell nanoclusters were analyzed both in vacuum and in oxidative environment. From the calculated segregation energies for the bimetallic and trimetallic nanoclusters in vacuum, it can be clearly observed that the M atoms prefer to be in the center of the M₆@Pd₃₈ and M₆@Pd₃₀Pt₈ nanoclusters. Nevertheless, it is observed that the segregation energies of M atoms for the M₆@Pd₃₈ nanoclusters with an oxidizing environment tend to decrease compared with their M₆@Pd₃₈ nanoclusters counterparts in vacuum, which suggests that in an oxidative environment, M atoms may tend to segregate to the surface of the M₆@Pd₃₈ nanoclusters.     

Solid State Analysis of Metal-Containing Polymers Employing Mössbauer Spectroscopy, Solid State NMR and F EI TOF MALDI MS

Polymers in general and metal-containing polymers in particular are often sparingly soluble or insoluble, in contrast to small molecules. Thus, special significance is attached to characterization techniques that can be applied to the materials as solids. Here, three techniques are discussed that give structural information gained from the solid material. Mössbauer spectroscopy is a powerful technique that may give information on the structure about the metal-containing moiety for about 44 different nuclei. Its use in describing the structure of the product obtained from organotin dichlorides and the unsymmetrical ciprofloxacin is presented along with the reaction implications of the results. Solid state NMR is also a useful tool in describing the structure of metal-containing polymers and its use is briefly described. Finally, MALDI MS can be used to gain structural information. For many metals it is particularly useful because of the presence of different isotopes that allow the identification of units through comparison of these isotope abundances with ion fragment clusters. Each of these tools can provide important structural characterization information.     

Normal molecular repair mechanisms in regenerative peripheral nerve interfaces allow recording of early spike activity despite immature myelination

Clinical use of neurally controlled prosthetics has advanced in recent years, but limitations still remain, including lacking fine motor control and sensory feedback. Indwelling multi-electrode arrays, cuff electrodes, and regenerative sieve electrodes have been reported to serve as peripheral neural interfaces, though long-term stability of the nerve-electrode interface has remained a formidable challenge. We recently developed a regenerative multi-electrode interface (REMI) that is able to record neural activity as early as seven days post-implantation. While this activity might represent normal neural depolarization during axonal regrowth, it can also be the result of altered nerve regeneration around the REMI. This study evaluated high-throughput expression levels of 84 genes involved in nerve injury and repair, and the histological changes that occur in parallel to this early neural activity. Animals exhibiting spike activity increased from 29% to 57% from 7 to 14 days following REMI implantation with a corresponding increase in firing rate of 113%. Two weeks after implantation, numbers of neurofilament-positive axons in the control and REMI implanted nerves were comparable, and in both cases the number of myelinated axons was low. During this time, expression levels of genes related to nerve injury and repair were similar in regenerated nerves, both in the presence or absence of the electrode array. Together, these results indicate that the early neural activity is intrinsic to the regenerating axons, and not induced by the REMI neurointerface.     

Durability and microstructure analysis of CO2-cured cement-bonded wood particleboard

Dry-processed cement-based wood composites are reconstituted wood products with desirable longevity, fire resistance and life cycle cost. In this study, the effects of accelerated aging on the performance of CO₂-cured cement-bonded wood particleboards were investigated. The accelerated aging conditions considered simulated natural aging phenomena. Repeated wetting–drying and freezing–thawing cycles led to increased stiffness and somewhat reduced toughness. X-ray diffraction and thermogravimetric analyses indicated that aging effects led to increased CaCO₃ and decreased Ca(OH)₂ contents in CO₂-cured cementitious composites. Mercury intrusion porosimetry test results indicated that CO₂ curing reduced the capillary pore volume in both unaged and aged boards.     

Experimental study of retrofitted reinforced concrete shear wall and concrete-encased steel girders using a new CarbonFlex composite for damage stabilization

A bi-axially loaded shear wall and two fatigue-damaged concrete-encased steel girders are experimentally tested using a retrofit technique that utilizes a newly developed composite wrap. The composite, which is being termed “CarbonFlex,” helps to stabilize the propagation of damage, specifically fracture, in retrofitted beams and a shear wall via an energy dissipation mechanism, resulting in significant ductility and confinement, and high-strength sustainability. The CarbonFlex-retrofitted shear wall had been initially damaged to a level corresponding to 40% of its peak strength under bi-axial loading (constant vertical load and quasi-static cyclic lateral load). Following the CarbonFlex-retrofit, the capacity doubled to 80% of its original strength while exhibiting significant ductility and having tremendously improved confinement. The fatigue-damaged beams are retrofitted using conventional carbon–fiber reinforced polymers (CFRPs), and then, separately, using the new prototype CarbonFlex composite. The latter beam sustained over 68% of its peak strength following dissipation of the initial shock energy of the fractured welds of the encased steel girder; the beam also exhibited significant displacement ductility, having an ultimate displacement three times that of its CFRP counterpart.     

Preliminary Results for the Inhibition of Pancreatic Cancer Cells by Organotin Polymers

Pancreatic cancer kills nearly all patients within 3–6 months after detection. There is no effective chemotherapy for it. We have found a number of organotin polymers that are effective at inhibiting pancreatic cancer cell lines with Chemotherapeutic Index values greater than two with some to values of 50.