Moisture diffusion through nanoclay/vinylester processed using twin‐screw extrusion

This research concerns moisture absorption through nanoclay/vinylester composites in artificial seawater medium and the resulting properties of degradation. Cloisite 15A, an organomodified nanoclay, and Cloisite Na, a naturally occurring nanoclay, were studied to examine the influence of organomodification on the moisture ingress behavior of the nanocomposites processed by using ultrasonication and twin‐screw extrusion. Although X‐ray diffraction and transmission electron microscopy analysis revealed exfoliation of Cloisite 15A in vinylester, Cloisite Na was only intercalated. Moisture diffusivity decreased by 72% due to the addition of 5 wt% of Cloisite 15A to vinylester. However, the same increased in the case of the addition of Cloisite Na, suggesting a positive influence of the organomodification on the moisture barrier properties. Although Fick's Law of Diffusion showed deviation from the experimental data in the nonlinear region of moisture absorption as a function of duration of exposure, the Langmuir Model was in better agreement with the experimental data in the entire range. (Cloisite 15A)/vinylester showed lower levels of microhardness deterioration due to moisture absorption than that of (Cloisite Na)/vinylester. J. VINYL ADDIT. TECHNOL., 20:152–159, 2014. © 2014 Society of Plastics Engineers     

Mechanical properties of vinylester/glass and polyester/glass composites fabricated by resin transfer molding and hand lay‐up

This paper reports the comparative performance of vinylester/glass and polyester/glass laminates fabricated by resin transfer molding (RTM) and hand lay‐up. A resin transfer mold was designed and fabricated for preparing the laminates. Void content was much lower in Spartan II RTM specimens than in that of hand lay‐up. Ultimate tensile strength, Young's modulus, flexural strength, flexural modulus, impact strength, and interlaminar shear strength of RTM specimens were superior to that of the hand lay‐up for both vinylester/glass and polyester/glass. The improvements for vinylester/glass were 44%, 28%, 88%, 84%, 36%, and 78% for the respective properties. The corresponding improvements for polyester/glass were 21%, 52%, 70%, 74%, 57%, and 82%, respectively. Particle impact erosion rate was lower in RTM specimens than that of the hand lay‐up. J. VINYL ADDIT. TECHNOL. 21:166–173, 2015. © 2014 Society of Plastics Engineers     

MODIFIED ATMOSPHERE AND VACUUM PACKAGING OF MEAT AND POULTRY PRODUCTS

Extension of the shelf-life of meat and poultry products is one of the technology needs to meet the demands of consumers. In this respect, increasing attention is put on packaging techniques. Modified atmosphere packaging (MAP) and vacuum packaging (VP) are recent innovations that have been gaining importance as preservation techniques to improve the shelf-life of meat and poultry. MAP provides alterations of atmospheric gas concentrations in the pack. Controlled atmosphere (CA) packaging is also MAP, wherein the selected atmospheric concentration of gas is actively maintained throughout the storage period. In VP, air is completely removed. The three principal gases used in MAP are carbon dioxide (to inhibit bacteria and moulds), nitrogen (to avoid oxidation of fats and pack collapse), and oxygen (to prevent anaerobic growth). Retention of meat color is better in MAP than in VP. However, color is regained when meat is removed from VP packets and exposed to air. Microbial profiles of MAP- and VP-meat do not differ significantly. MAP offers several unique advantages for retaining the desirable market quality of products. The safety of MAP meat is still a concern under temperature abuse conditions but it can be improved by coupling with hurdle technology and proper preservation systems. Active packaging is a significant area of advancement of MAP technology to further improve the safety of meat and poultry products. This contribution critically reviews the existing knowledge on MAP and VP of meat and poultry in order to broaden our understanding of the subject and to suggest further areas of research to effectively use these technologies for marketing safe meat and poultry products.     

Growth of textured films of BiSCCO from alkali halide solutions

Films of Bi-Sr-Ca-Cu-O with lead doping using SrF₂ substrates have been grown from KCl solution. The films were highly textured withC-axis perpendicular to the substrate surface. The onset of the resistive transition was at 81 K and zero resistance at 78 K. This technique is permising in view of the possibility to grow large films of both Bi₂Sr₂CaCu₂O _x and Bi₂Sr₂Ca₂Cu₃O _y phases.     

The role of the paternal genome in the development of the mouse germ line

The mouse germ line originates at 6.5 days post coitum (dpc) in the proximal epiblast, apparently in response to signals from the primitive endoderm or the extraembryonic mesoderm [1,2]. Some studies have implied a significant role for imprinted genes in germ-line development [3,4]. These genes, whose expression is determined by their parental origin [5], serve complementary functions during mammalian development [6-9] and exert striking reciprocal phenotypic effects on androgenetic (AG: two paternal genomes) and parthenogenetic (GG/PG: two maternal genomes) cells [3,4,10]. This may include a fundamental effect on germ-cell development because PG but not AG cells can differentiate into viable gametes [3,4,11], suggesting that the maternal genome is obligatory for development of the mammalian germ line. Here we show unequivocally that AG cells can differentiate into germ cells, and that in chimeras with normal cells they produce functional sperm. These studies establish that the paternal and maternal genomes can individually provide both the signal and the response required for the specification of germ cells in mammals.     

A rigorous variational formulation of an H planeslot-coupled tee junction

A rigorous analysis for the determination of an exact equivalent network for the slot-coupled H-plane tee junction that takes the effect of wall thickness into account is presented. A variational formulation is used for the determination of the parameters of the network. The parameters of the S-matrix as well as coupling are evaluated from the exact equivalent network. Comparisons between theoretical and experimental results are presented     

Vortex simulation of turbulent mixing layers

We present here a brief survey of vortex-dynamical simulations of the plane mixing layer using different forms of vortex elements. Points and blobs, which have been widely used in the past, suffer from irregular evolution of the vortex sheet approximating the shear layer, and the rather long time-averaging required to obtain meaningful statistics. A technique recently proposed by the authors, using vortex arcs or sheet elements, has been found to be helpful in avoiding these difficulties. In particular, this technique avoids the singularity in induced velocity associated with point vortex techniques, and is therefore in no need of any form of the “desingularization” that is often introduced in the latter. New results for excited mixing layers using the vortex sheet element model are presented, and are shown to be in good agreement with experimental observations.     

Code-selective frequency shifting by RF photonic mixing in a dual-electrode Mach-Zehnder modulator

Code-selective frequency shifting by RF photonic mixing that may be used to demultiplex direct sequence encoded CDMA signals in the optical domain has been demonstrated. The technique exploits the bipolar nature of the optical field without requiring an optical local oscillator, and spectrally isolates the desired channel before photodetection.     

Scanning Transmission Electron Microscope Analysis of Solute Partitioning in a Partially Stabilized Zirconia

Solute partitioning and grain-boundary chemistry in a commercial Y₂O₃-bearing partially stabilized zirconia were studied by scanning transmission electron microscopy. The ceramic contained a mixture of twinned monoclinic (minor) phase and cubic (major) phase. Fine-scale precipitation was noted within the cubic phase. The average measured YiO₃ concentrations in the two phases were near those that would be expected from the binary phase diagram, indicating that solute partitioning approaches completion.