The surface properties of carbon fibers and their adhesion to organic polymers

The state of knowledge of the surface properties of carbon fibers is reviewed, with emphasis on fiber/matrix adhesion in carbon fiber reinforced plastics. Subjects treated include carbon fiber structure and chemistry, techniques for the study of the fiber surface, polymer/fiber bond strength and its measurement, variations in polymer properties in the interphase, and the influence of fiber matrix adhesion on composite mechanical properties. Critical issues are summarized and search recommendations are made

Foremost Insurance Co. v. Richardson: If This Is Water, It Must Be Admiralty

This article will examine the two decisional approaches that the Richardson Court considered in support of the proposition that admiralty jurisdiction should not apply to the facts of the case before it, and will explore the shortcomings of each in an attempt to understand why the majority ultimately felt compelled to reject both. The article will then focus on the five specific arguments thought to mandate that rejection, demonstrating that the conclusion the Court reached is not logically supportable. Finally, a new approach to the issue will be forwarded, one that provides the basis for a more rational approach to the broad issue of admiralty tort jurisdiction

Stable Aqueous Suspension and Self-Assembly of Graphite Nanoplatelets Coated with Various Polyelectrolytes

Exfoliated graphite nanoplatelets (xGnPs) with an average thickness of 1–10 nm present an inexpensive alternative to carbon nanotubes in many applications. In this paper, stable aqueous suspension of xGnP was achieved by noncovalent functionalization of xGnP with polyelectrolytes. The surfactants and polyelectrolytes were compared with respect to their ability to suspend graphite nanoplatelets. The surface charge of the nanoplatelets was characterized with zeta potential measurements, and the bonding strength of the polymer chains to the surface of xGnP was characterized with Raman spectroscopy. This robust method opens up the possibility of using this inexpensive nanomaterial in many applications, including electrochemical devices, and leads to simple processing techniques such as layer-by-layer deposition. Therefore, the formation of xGnP conductive coatings using layer-by-layer deposition was also demonstrated

Spin tunnelling in mesoscopic systems

We study spin tunnelling in molecular magnets as an instance of a mesoscopic phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel splitting between various pairs of Zeeman levels in this molecule oscillates as a function of applied magnetic field, vanishing completely at special points in the space of magnetic fields, known as diabolical points. This phenomena is explained in terms of two approaches, one based on spin-coherent-state path integrals, and the other on a generalization of the phase integral (or WKB) method to difference equations. Explicit formulas for the diabolical points are obtained for a model Hamiltonian.Comment: 13 pages, 5 figures, uses Pramana style files; conference proceedings articl

Contributions of obesity to kidney health and disease: insights from Mendelian randomization and the human kidney transcriptomics

AIMS: Obesity and kidney diseases are common complex disorders with an increasing clinical and economic impact on healthcare around the globe. Our objective was to examine if modifiable anthropometric obesity indices show putatively causal association with kidney health and disease and highlight biological mechanisms of potential relevance to the association between obesity and the kidney. METHODS AND RESULTS: We performed observational, one-sample, two-sample Mendelian randomization (MR) and multivariable MR studies i

The long‐term effects on children and adolescents of a policy providing work supports for low‐income parents

New Hope, an employment‐based poverty‐reduction intervention for adults evaluated in a random‐assignment experimental design, had positive impacts on children's achievement and social behavior two and five years after random assignment. The question addressed in this paper was the following: Did the positive effects of New Hope on younger children diminish or even reverse when children reached the challenges of adolescence (eight years after random assignment)? Small positive impacts on school progress, school motivation, positive social behavior, child well‐being, and parent control endured, but impacts on school achievement and problem behavior were no longer evident. The most likely reasons for lasting impacts were that New Hope families were slightly less likely to be poor, and children had spent more time in center‐based child care and structured activities. New Hope represents a model policy that could produce modest improvements in the lives of low‐income adults and children. © 2011 by the Association for Public Policy Analysis and Management.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87035/1/20613_ftp.pd

The Impact of Damage Accumulation on the Kinetics of Network Strength Recovery for a Physical Polymer Gel Subjected to Shear Deformation

Shear rheophysical experiments were used to quantify the kinetics of strength recovery of model thermoreversible polymer gels that were fractured and ultimately sheared to different total magnitudes of strain (700 and 4000%) before resting for set periods of time. Relationships between the amount of strength recovered and the normalized ratio of resting times to characteristic relaxation times were developed. It was found that gels displayed fully healed networks within timescales that were 2-3 orders of magnitude greater than the gel’s characteristic relaxation time. Gels deformed to 700% applied strain either healed slower at lower gel concentrations as compared to experiments at larger applied strains due to possible viscous heating or healed faster from incomplete fracture propagation for higher gel concentrations

Completely discontinuous organic/ inorganic hybrid nanocomposites by self-curing of nanobuilding blocks constructed from reactions of [HMe 2 SiOSiO 1.5 ] 8 with vinylcyclohexene

The reaction of 4-vinyl-1-cylcohexene with [HMe 2 SiOSiO 1.5 ] 8 provides tetra- and octa-2-cyclohexenylethyloctasilsesquioxanes. The tetrabifunctional [cyclohexenylethylMe 2 SiOSiO 1.5 ] 4 -[HMe 2 SiOSiO 1.5 ] 4 (average degree of functionalization) melts near 80 °C and can be cast and then cured (by thermal hydrosilylation) into transparent nanocomposite shapes. These materials, while not nanoporous, offer dielectric constants of 2.8–2.9 at 100 kHz to 3 MHz, and are air stable to temperatures ≥ 400 °C. The resulting materials appear (by X-ray diffraction) to be partially ordered after curing. The octafunctional material also melts at low temperatures ( ca 120 °C) and can be copolymerized with hydridosiloxanes to give similar materials with lower thermal stability. The synthesis and characterization of the starting materials is described, as well as thermal curing studies and properties characterization of the resultant nanocomposites. Copyright © 2007 Society of Chemical IndustryPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57384/1/2281_ftp.pd