Antimicrobial Activity of Nisin and Natamycin Incorporated Sodium Caseinate Extrusion‐Blown Films: A Comparative Study with Heat‐Pressed/Solution Cast Films

Antimicrobial edible films based on sodium caseinate, glycerol, and 2 food preservatives (nisin or natamycin) were prepared by classical thermomechanical processes. Food preservatives were compounded (at 65 °C for 2.5 min) with sodium caseinate in a twin‐screw extruder. Anti‐Listeria activity assays revealed a partial inactivation of nisin following compounding. Thermoplastic pellets containing food preservatives were then used to manufacture films either by blown‐film extrusion process or by heat‐press. After 24 h of incubation on agar plates, the diameters of K. rhizophila growth inhibition zones around nisin‐incorporated films prepared by solution casting (control), extrusion blowing or heat pressing at 80 °C for 7 min of nisin‐containing pellets were 15.5 ± 0.9, 9.8 ± 0.2, and 8.6 ± 1.0 mm, respectively. Since heat‐pressing for 7 min at 80 °C of nisin‐incorporated pellets did not further inactivate nisin, this indicates that nisin inactivation during extrusion‐blowing was limited. Moreover, the lower diameter of the K. rhizophila growth inhibition zone around films prepared with nisin‐containing pellets compared to that observed around films directly prepared by solution casting confirms that nisin inactivation mainly occurred during the compounding step. Natamycin‐containing thermoplastic films inhibited Aspergillus niger growth; however, by contrast with nisin‐containing films, heat‐pressed films had higher inhibition zone diameters than blown films, therefore suggesting a partial inactivation of natamycin during extrusion‐blowing.     

Quantum-inspired design of resilient substitution boxes: From coding to hardware implementation

S-boxes constitute a cornerstone component in symmetric-key cryptographic algorithms, such as DES and AES encryption systems. In block ciphers, they are typically used to obscure the relationship between the plaintext and the ciphertext. Non-linear and non-correlated S-boxes are the most secure against linear and differential cryptanalysis. In this paper, we focus on a twofold objective: first, we evolve regular S-boxes with high non-linearity and low auto-correlation properties; then automatically generate evolvable hardware for the obtained S-box. Targeting the former, we use a quantum-inspired evolutionary algorithm to optimize regularity, non-linearity and auto-correlation, which constitute the three main desired properties in resilient S-boxes. Pursuing the latter, we exploit the same algorithm to automatically generate the evolvable hardware designs of substitution boxes that minimize hardware space and encryption/decryption time, which form the two main hardware characteristics. We compare our results against existing and well-known designs, which were produced by using conventional methods as well as through genetic algorithm. We will show that our approach provides higher quality S-boxes coding as well as circuits.     

Thermally stable antimicrobial polyvinylchloride/maleimido aromatic hydrazide composites

Antimicrobial novel substituted maleimido aromatic hydrazides were synthesized from N‐[4‐(chlorocarbonyl) phenyl] maleimide with salicylhydrazide, p‐aminobenzohydrazide, or p‐aminosalicylhydrazide. They were characterized by Fourier transform infrared (FTIR), hydrogen‐1 nuclear magnetic resonance (¹H‐NMR), mass spectra, elemental analyses, and antimicrobial activities. These derivatives were investigated as thermal stabilizers for rigid poly(vinyl chloride) (PVC) at 180°C in air by measuring the rate of dehydrochlorination, the extent of discoloration, and the changes that occurred in the molecular masses of the degraded PVC samples. The previously reported stabilizing efficiency data of a nonsubstituted derivative, which was synthesized from N‐[4‐(chlorocarbonyl) phenyl] maleimide with benzohydrazide, is also given for comparison. The results reveal the greater stabilizing efficiency of the investigated derivatives as shown by their longer thermal stability (Ts) periods and lower dehydrochlorination rates in relation to dibasic lead carbonate, cadmium‐barium‐zinc stearate, and n‐octyltin mercaptide industrial stabilizers. The stabilizing efficiency increases with the introduction of electron donating substituent groups in the aromatic ring of the stabilizer molecules. Moreover, the investigated stabilizers impart better color stability for the degraded samples as compared with the reference stabilizers. A synergistic effect is achieved when the materials under investigation were mixed in various weight ratios with any of the reference stabilizers, reaching its maximum at equivalent weight ratio of the investigated stabilizer to the reference one. J. VINYL ADDIT. TECHNOL., 22:247–258, 2016. © 2014 Society of Plastics Engineers     

Does carbon nanopowder threaten amphibian development?

Lethal and teratogenic potentials of carbon nanoparticles (CNPs) in their amorphous form were investigated by the standardized Frog Embryo Teratogenesis Assay-Xenopus (FETAX), a 96-h in vitro whole-embryo toxicity test based on the amphibian Xenopus laevis. Embryos were acutely exposed to 1, 10, 100 and 500 mg/L CNP suspensions and evaluated for lethality, malformations and growth inhibition. Larvae were processed for histological and ultrastructural analyses to detect the main affected organs, to look for specific lesions at the subcellular level and to image and track CNPs into tissues. Only the highest CNP suspension resulted in being embryolethal for X. laevis larvae, while malformed larva percentages significantly differed from controls starting from 100 mg/L. The stomach and gut were the preferential CNP accumulation sites, on the contrary, the digestive epithelium remained intact. The analyses showed the presence of isolated nanoparticles and/or aggregates in different secondary target organs. CNPs were found in circulating erythrocytes. The research confirms the good tolerance of X. laevis towards pure elemental carbon in its nanoparticulate amorphous form, but highlights the possibility of CNP transfer toward all body areas.     

Effect of extra virgin olive oil on glycaemia in healthy young subjects

In this approach we studied the glycaemia levels in 20 healthy young volunteers (26 ± 2 years), before and after a 30‐day intake of 50 mL of extra virgin olive oil (EVOO). We selected an oil rich in phenolic compounds (523 mg/L) with a high content of secoiridoidic derivatives (over 94.5%). The findings from our study reveal a significant decrease of glycaemia from 89.6 ± 6.8 to 82.7 ± 10.3 mg/dL (p<0.05), related to a long term daily intake of the study EVOO, as the only added fat. A significant increment of the HDL cholesterol, from 68.7 ± 11.5 to 75.2 ± 4.9 mg/dL, was also highlighted. Total cholesterol, LDL, VLDL, triglycerides, and blood pressure did not show significant variation after the 30‐day consumption of this EVOO. So far, few articles have described the influence of EVOO consumption, on plasma glucose levels in humans. This effect is observed in a group of healthy young humans. Moreover, we confirm that the level of free hydroxytyrosol (OH‐Tyr) in plasma increased up to fourfold (p<0.05) after the 30‐day intake of this EVOO. In addition, the excretion in urine of the main metabolite of OH‐Tyr, homovanillic acid (HVA), significantly increased.     

Temperature and electric field dependent hole mobility in a polyfluorene copolymer

Transport of holes in thin films of a low-bandgap alternating polyfluorene copolymer, APFO-Green5, was investigated by means of admittance spectroscopy as a function of field and temperature. The values of hole mobility were evaluated from the position of the maxima in the plots of the negative differential susceptance as a function of frequency. Hole mobility was found to be strongly field- and temperature-dependent. The charge transport parameters were extracted by analyzing the mobility data by the uncorrelated and the correlated Gaussian Disorder Models.     

Megasonic agitation for enhanced electrodeposition of copper

In this paper we propose an agitation method based on megasonic acoustic streaming to overcome the limitations in plating rate and uniformity of the metal deposits during the electroplating process. Megasonic agitation at a frequency of 1 MHz allows the reduction of the thickness of the Nernst diffusion layer to less than 600 nm. Two applications that demonstrate the benefits of megasonic acoustic streaming are presented: the formation of uniform ultra-fine pitch flip-chip bumps and the metallisation of high aspect ratio microvias. For the latter application, a multi-physics based numerical simulation is implemented to describe the hydrodynamics introduced by the acoustic waves as they travel inside the deep microvias.     

Modeling and solving a one-supplier multi-vehicle production-inventory-distribution problem with clustered retailers

This paper considers a supply chain management problem which integrates production, inventory, and distribution decisions. The supply chain is composed of one supplier production facility and several retailers located in a given geographic region. The supplier is responsible for the production and the replenishment of the inventory of retailers, in a vendor managed inventory (VMI) context. The distance between retailers is negligible compared to the distance between the supplier and the retailers’ region. Thus, for each vehicle, there is a major fixed cost for traveling to the cluster of retailers and a minor fixed cost for visiting each individual retailer. The problem consists of determining quantities to be produced, quantities to be delivered to retailers, vehicles to be used, and retailers to be serviced by each vehicle. This problem is an extension of the one warehouse multi-retailer problem with the consideration of production planning and storage and vehicle capacity limitations in addition to fixed vehicle utilization costs and retailer servicing costs. The objective is to minimize a total cost composed of production, transportation, and inventory holding costs at the supplier and at the retailers. Two mixed integer linear programming formulations are proposed and six families of valid inequalities are added to strengthen these formulations. Two of these families are new and the others are adapted from the literature. The numerical results show that the valid inequalities considerably improve the quality of the formulations. Moreover, the parameters that influence the most computational times are analyzed.