The effect of chronic streptozotocin-induced diabetes on phospholipid metabolism in rat sciatic nerve in vitro was investigated. In normal nerve incubated for 2 h in Krebs-Ringer-bicarbonate buffer containing [32P]orthophosphate, radioactivity was primarily incorporated into phosphatidylinositol-4,5-bisphosphate and phosphatidylcholine. Smaller amounts were present in phosphatidylinositol-4-phosphate, phosphatidylinositol, and phosphatidic acid. As compared to controls, phosphatidylinositol-4,5-bisphosphate in nerves from animals made diabetic 2, 10, and 20 weeks earlier accounted for 30-46% more of the isotope, expressed as a percentage, incorporated into all phospholipids. In contrast, the proportion of radioactivity in phosphatidylcholine decreased by 10-25%. When the results were expressed as the quantity of phosphorus incorporated into phospholipid, only phosphatidylinositol-4,5-bisphosphate displayed a change. The amount of isotope which entered this lipid increased 60% and 67% for 2- and 10-week diabetic animals, respectively. Increased phosphatidylinositol-4,5-bisphosphate labeling was observed when epineurial-free preparations were used or when the composition of the incubation medium was varied. Sciatic and caudal nerve conduction velocities were decreased after 10 and 20 weeks but were unchanged after 2 weeks. We conclude that an increase in the turnover of phosphatidylinositol-4,5-bisphosphate in sciatic nerve from streptozotocin-diabetic rats appears relatively early and persists throughout the course of the disease. This metabolic alteration may be related to a primary defect responsible for the accompanying deficient peripheral nerve function.

Polyethylene and nanosilica represent the most ubiquitous commodity plastic and nanocomposite filler, respectively. Despite their potential utility, few examples exist in the literature of successfully combining these two materials to form polyethylene nanocomposites. Synthesizing well-defined polyethylene grafted to a surface is a significant challenge in the nanocomposites community. Presented here is a synthetic approach toward polyethylene grafted nanoparticles with controllable graft density and molecular weight of the grafted polymer. The variably grafted nanoparticles were then incorporated into a commercial high density polyethylene matrix. The synthesis, characterization, and challenges in making these materials are discussed.

The central goal of dielectric nanocomposite design is to create a large interfacial area between the matrix polymer and nanofillers and to use it to tailor the properties of the composite. The interface can create sites for trapping electrons leading to increased dielectric breakdown strength (DBS). Nanoparticles with a bimodal population of covalently anchored molecules were created using ligand engineering. Electrically active short molecules (oligothiophene or ferrocene) and matrix compatible long poly(glycidyl methacrylate) (PGMA) chains comprise the bimodal brush. The dielectric breakdown strength was evaluated from recessed samples and dielectric spectroscopy was used to study the dielectric constant and loss as a function of frequency. The dielectric breakdown strength and permittivity increased considerably with only 2 wt% filler loading while the dielectric loss remained comparable to the reference epoxy.

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In this article, we report the synthesis of a new bimodal surface ligand morphology on silica nanoparticles. Combining grafting-to and grafting-from approaches, in this study, we demonstrated the efficacy of anthracene surface modification for improving the dielectric breakdown strength (DBS) under alternating-current and direct-current conditions and that of a matrix-compatible polymer brush for controlling the nanofiller (NF) dispersion. Ligand-modified spherical colloidal SiO 2 nanoparticles (14 nm in diameter) were mixed into polypropylene, and the resulting dispersion was improved over the unmodified particles, as shown with transmission electron microscopy. The results suggest that the electronic structure of the anthracene-modified particle surface was critical to the improvement in DBS. In addition, the DBS of the composite was shown to depend on the dispersion state of the filler and the mode of stress; this indicated that the individually dispersed nanoparticles were not necessarily the optimal morphology for all stress conditions. Additionally, the precise nature of the matrix-compatible brush was less important than the NF dispersion it produced. The bimodal grafted architectural design has provided a promising solution for the control of the dispersion and surface properties, especially for high-molecular-weight polymer matrices.