Cavity size, sorption and transport characteristics of thermally rearranged (TR) polymers

Within a polymer thin film, free volume elements have a wide range of size and topology. This broad range of free volume element sizes determines the ability for a polymer to perform molecular separations. Herein, six permeable thermally rearranged (TR) polymers and their precursors were studied. Using atomistic models, cavity size (free volume) distributions determined by a combination of molecular dynamics and Monte Carlo methods were consistent with experimental observation that TR polymers are more permeable than their precursors. The cavity size distributions determined by simulation were also consistent with free volume distributions determined by positron annihilation lifetime spectroscopy. The diffusion, solubility and permeation of gases in TR polymers and their precursors were also simulated at 308 K, with results that agree qualitatively with experimental data.     

Bidirectional Mobile Code Trust Management Using Tamper Resistant Hardware

Trust management in a networked environment consists of authentication and integrity checking. In a mobile computing environment, both remote hosts and mobile code are suspect. We present a model that addresses trust negotiation between the remote host and the mobile code simultaneously. Our model uses tamper resistant hardware, public key cryptography, and one-way hash functions.     

The Indiana silicon sphere 4π charged-particle detector array

A low threshold charged particle detector array for the study of fragmentation processes in light-ion-induced reactions has been constructed and successfully implemented at the IUCF and Saturne II accelerators. The array consists of 162-triple-element detector telescopes mounted in a spherical geometry and covering 74% of 4π in solid angle. Telescope elements are composed of (1) an axial-field gas ionization chamber operated with C₃F₈ gas; (2) a 0.5 mm thick passivated silicon detector, and (3) a 2.8 cm thick CsI(Tl) scintillation crystal with photodiode readout. Discrete element identification is obtained for ejectiles up to Z 16 over the dynamic range 0.7 ≤ E/A ≤ 95 MeV/nucleon. Isotopes are also distinguished for H, He, Li and Be ejectiles with 8 E/A 95 MeV. Custom-designed electronics are employed for bias supplies and linear signal processing. Data are acquired via a CAMAC/VME/Ethernet system.     

Fusarium graminearum A 3/5 as a novel host for heterologous protein production

We describe a novel fungal expression system which utilizes the Quorn myco-protein fungus Fusarium graminearum A 3/5. A transformation system was developed for F. graminearum and was used to introduce the coding and regulatory regions of a trypsin gene from Fusarium oxysporum. The protein was efficiently expressed, processed and secreted by the recombinant host strain. In addition, the promoter and terminator of the F. oxysporum trypsin gene have been successfully utilized to drive the expression of a cellulase gene from Scytalidium thermophilum and a lipase gene from Thermomyces lanuginosus in F. graminearum.     

Nurse and patient reactions to social displays of depression.

Examined the interpersonal responses of 27 nurses and 27 hospitalized patients with chronic medical conditions to a target who appeared either to have a chronic physical impairment or to be able-bodied, and who enacted either a depressed or nondepressed role. It was predicted that while nurses and patients would have negative reactions to the depressed targets, patient reactions to the depressed target with a physical impairment would be less negative than nurse reactions on the basis of perceived similarity. Results indicated that both groups had negative perceptions of the depressed targets. The similarity hypothesis, however, was not explicitly supported. The reactions of health-care staff to depressed medical patients may reinforce the patients' depressive behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nanocrystal-semiconductor interface: Atomic-resolution cross-sectional transmission electron microscope study of lead sulfide nanocrystal quantum dots on crystalline silicon

We report on a cross-sectional high resolution transmission electron microscope study of lead sulfide nanocrystal quantum dots （NCQDs） dispersed on electron-transparent silicon nanopillars that enables nearly atomically-resolved simultaneous imaging of the entire composite： the quantum dot, the interfacial region, and the silicon substrate. Considerable richness in the nanocrystal shape and orientation with respect to the substrate lattice is observed. The average NCQD-substrate separation is found to be significantly smaller than the length of the ligands on the NCQDs. Complementary photoluminescence measurements show that light emission from PbS NCQDs on silicon is effectively quenched which we attribute to intrinsic mechanisms of energy and charge transfer from PbS NCQDs to Si.     

Quantitative MRI study of water distribution during operation of a PEM fuel cell using Teflon flow fields

Water management remains a leading challenge in the implementation of small polymer electrolyte membrane (PEM) fuel cells for portable electronic applications. At present there are many excellent models for the distribution of water within PEM fuel cells, but little quantitative data on the water distribution that can be compared to models.