Rheological behavior of polypropylene nanocomposites at low concentration of surface modified carbon nanotubes

This article reports the rheological behavior of nanocomposites of isotactic polypropylene with both unmodified multiwall carbon nanotubes (CNTs) and phenol and 1‐octadecanol (C18) functionalized CNT (f‐CNT) at 0.1, 0.25, 1.0, and 5.0 wt% of the nanofillers. The incorporation of CNT at low loadings of 0.1 and 0.25 wt% decreases the storage and loss modulus and complex viscosity of the system, especially for the case of using f‐CNT. Out of the two types of functionalizations, C18 functionalization registers the lowest modulus and viscosity and displays processing aid behavior at 0.1 wt% loading, which is believed to be due to the disruption of the polymer entanglements. As the nanofiller loading increases to 1 wt%, the disruption of polymer entanglements effect is balanced by the hydrodynamic effect and subsequently neat polypropylene (PP), and the filled PP systems show similar modulus and complex viscosity. As the nanofiller loading increases further to 5 wt%, the hydrodynamic effect becomes the dominating factor, and the modulus and the complex viscosity of the nanofilled system become greater than that of neat PP. Results suggest that the 0.1 wt% loading of C18 f‐CNT could be a useful processing aid additive for improving polypropylene processability. POLYM. ENG. SCI., 52:1868–1873, 2012. © 2012 Society of Plastics Engineers     

Prevalence of helminth parasites found on vegetables sold in Maiduguri, Northeastern Nigeria

Background

For a healthy diet, people have been encouraged to eat lots of raw (fresh) vegetables and these can serve as vehicles of transmitting enteric parasitic pathogens throughout the process of planting to consumption. The aim of the present study was to determine the prevalence of helminth parasites found on vegetables sold in Maiduguri, northeastern Nigeria.

Methods

A total of 1130 samples of fresh salad vegetables obtained from retail markets were examined for helminth eggs and larvae by using standard methods.

Results

Out of the 300 lettuce, 250 cabbage, 200 garden egg, 150 carrot, 130 cucumber and 100 green-peppers samples examined, eggs of Ascaris spp., hookworm, Trichuris spp., Taenia/Echinococcus spp., and Strongyloides stercoralis were detected in 0.5%, 1.2%, 0.5%, 0.5%, and 0.6% respectively of all samples. The lettuce, cabbage, garden-egg, carrot, and cucumber samples were 8.2%, 2.0%, 1.0%, 1.3%, 2.3% contaminated with helminth parasites respectively with an overall prevalence of 3.5%. No helminth parasites were detected in green-peppers. Vegetables from the Gamboru Market were contaminated with helminth parasites more than the other markets (P < 0.05).

Conclusion

Proper washing of vegetables is imperative for a healthy diet as the results of this study showed the presence of helminth parasites from raw vegetables used as salads in Nigeria.     

Cold-Active Lipases and Esterases: A Review on Recombinant Overexpression and Other Essential Issues

Cold environments characterised by diverse temperatures close to or below the water freezing point dominate about 80% of the Earth’s biosphere. One of the survival strategies adopted by microorganisms living in cold environments is their expression of cold-active enzymes that enable them to perform an efficient metabolic flux at low temperatures necessary to thrive and reproduce under those constraints. Cold-active enzymes are ideal biocatalysts that can reduce the need for heating procedures and improve industrial processes’ quality, sustainability, and cost-effectiveness. Despite their wide applications, their industrial usage is still limited, and the major contributing factor is the lack of complete understanding of their structure and cold adaptation mechanisms. The current review looked at the recombinant overexpression, purification, and recent mechanism of cold adaptation, various approaches for purification, and three-dimensional (3D) crystal structure elucidation of cold-active lipases and esterase.