Molecular Origin of Strain-Induced Chain Alignment in PDPP-Based Semiconducting Polymeric Thin Films

Donor–acceptor (D–A) type semiconducting polymers have shown great potential for the application of deformable and stretchable electronics in recent decades. However, due to their heterogeneous structure with rigid backbones and long solubilizing side chains, the fundamental understanding of their molecular picture upon mechanical deformation still lacks investigation. Here, the molecular orientation of diketopyrrolopyrrole (DPP)-based D–A polymer thin films is probed under tensile deformation via both experimental measurements and molecular modeling. The detailed morphological analysis demonstrates highly aligned polymer crystallites upon deformation, while the degree of backbone alignment is limited within the crystalline domain. Besides, the aromatic ring on polymer backbones rotates parallel to the strain direction despite the relatively low overall chain anisotropy. The effect of side-chain length on the DPP chain alignment is observed to be less noticeable. These observations are distinct from traditional linear-chain semicrystalline polymers like polyethylene due to distinct characteristics of backbone/side-chain combination and the crystallographic characteristics in DPP polymers. Furthermore, a stable and isotropic charge carrier mobility is obtained from fabricated organic field-effect transistors. This study deconvolutes the alignment of different components within the thin-film microstructure and highlights that crystallite rotation and chain slippage are the primary deformation mechanisms for semiconducting polymers.     

Full Gamut Wall Tunability from Persistent Micelle Templates via Ex Situ Hydrolysis

The predictive self‐assembly of tunable nanostructures is of great utility for broad nanomaterial investigations and applications. The use of equilibrium‐based approaches however prevents independent feature size control. Kinetic‐controlled methods such as persistent micelle templates (PMTs) overcome this limitation and maintain constant pore size by imposing a large thermodynamic barrier to chain exchange. Thus, the wall thickness is independently adjusted via addition of material precursors to PMTs. Prior PMT demonstrations added water‐reactive material precursors directly to aqueous micelle solutions. That approach depletes the thermodynamic barrier to chain exchange and thus limits the amount of material added under PMT‐control. Here, an ex situ hydrolysis method is developed for TiO₂ that mitigates this depletion of water and nearly decouples materials chemistry from micelle control. This enables the widest reported PMT range (M:T = 1.6–4.0), spanning the gamut from sparse walls to nearly isolated pores with ≈2 Å precision adjustment. This high‐resolution nanomaterial series exhibits monotonic trends where PMT confinement within increasing wall‐thickness leads to larger crystallites and an increasing extent of lithiation, reaching Li_0.66TiO₂. The increasing extent of lithiation with increasing anatase crystallite dimensions is attributed to the size‐dependent strain mismatch of anatase and bronze polymorph mixtures.     

HILT: a heavy ion large area proportional counter telescope forsolar and anomalous cosmic rays

The HILT sensor has been designed to measure heavy ion elemental abundances, energy spectra, and direction of incidence in the mass range from helium to iron and in the energy range 4-250 MeV/nucleon. With its large geometric factor of 60 cm² sr the sensor is optimized to provide compositional and spectral measurements for low-intensity cosmic rays, i.e., for small solar energetic particle events and for the anomalous component of cosmic rays. The instrument combines a large-area ion-drift-chamber-proportional-counter system with two arrays of 16 Li-drifted solid state detectors and 16 CsI crystals. The multi-dE /dx-E technique provides a low-background mass and energy determination. The sensor also measures particle direction. By combining these measurements with the information on the spacecraft position and attitude in the low-altitude polar orbit, it will be possible to infer the ionic charge of the ions from the local cutoff of the Earth's magnetic field. The ionic charge in this energy range is of particular interest because it provides unique clues to the origin of these particles and has not been investigated systematically so far     

A Device for Zero-Eye-Movement Reading

A portable personal computer has been programmed as a flexible and economical text display device capable of delivering single and multiple words or symbols flashed in the center of the screen with a wide range of repetition times and duty cycles (fraction of stimulus on/off time). All aspects of a computer-controlled experiment are controlled by a command file which can be created by workers with basic word processing skills and no knowledge of computer programming. Digital output is provided for recording stimulus timing on a chart recorder or computer for comparison to eye movements or other externally recorded variables. The system is ideal for zero-eye-movement reading experiments in which sentences are flashed a word or group of words at a time in the center of a CRT screen. If the subject is then asked to repeat the sentence aloud, the percentage of words correctly recalled is a measure of "reading comprehension." Results with nine subjects match previous data [1] obtained cinematographically.     

Constitution and age hardening of Al-Sc alloys

Aluminium-rich alloys from the Al-Sc system were examined to determine the form of the equilibrium phase diagram and to obtain information on age hardening of chill cast alloys. Samples containing up to 8.75wt% Sc were examined using thermal analysis and optical microscopy. This work indicated a eutectic type of phase diagram with a eutectic temperature of about 665° C and a eutectic composition of about 0.6wt% Sc. The scandium-rich primary phase was found to be ScAl₃ which is f c c with a lattice parameter of 0.4105nm. Chill cast samples of a 1 wt% Sc alloy were examined for their age hardening behaviour over the temperature range of 225 to 360° C. A maximum hardness of 77 VHN was obtained after ageing at 250° C for 3 days. This hardness was retained after ageing for a total of at least 12 days. The hardening precipitates were ScAl₃ which were observed to form via a discontinuous precipitation mechanism. The ScAl₃ precipitates were observed to have a parallel orientation relationship with the matrix.     

Opiates and medial hypothalamic knife cuts cause hyperphagia through different mechanisms.

In Exp I, male Sprague-Dawley rats were given bilateral parasagittal medial hypothalamic knife cuts (KCs) or a sham procedure and fed a high-fat diet. KC and sham-operated Ss were approximately equally sensitive to the suppressive effects of naloxone (0.1–20 mg/kg, subcutaneously [sc]) on food intake. Ketocyclazocine (0.1–20 mg/kg, sc) generally increased daytime food intake in sham-operated Ss; in contrast, the normal hyperphagia of KC Ss was in most cases either unchanged or decreased by ketocyclazocine. In Exp II, neither diet composition nor hypothalamic KCs significantly affected the feeding responses to naloxone or the stimulatory effects of butorphanol tartrate (0.1–20 mg/kg, sc). It was hypothesized that the differential effects of ketocyclazocine in KC and sham-operated Ss were a consequence of the sedative effects of the drug combined with the elevated baseline of the KC Ss. This hypothesis was supported by Exp III, which showed that ketocyclazocine also reduced nocturnal intake in unoperated Ss and that butorphanol increased intake. That feeding responses to naloxone and butorphanol were essentially unchanged by hypothalamic KCs suggests that the opioid feeding system is independent of the longitudinal feeding inhibitory pathway believed to be involved in KC-induced hyperphagia. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The pathogenesis of gonococcal urethritis in men: confocal and immunoelectron microscopic analysis of urethral exudates from men infected with Neisseria gonorrhoeae

Confocal and immunoelectron microscopic analysis of urethral exudates from 12 men with gonococcal urethritis showed that Neisseria gonorrhoeae can invade urethral epithelial cells. Studies with acridine orange stain demonstrated that the majority of organisms within urethral epithelial cells were viable at the time of fixation. Three-dimensional modeling of an infected epithelial cell using image analysis of 21 digitized confocal sections stained with YOYO-1 and DiIC 18(3) revealed that gonococcal invasion of these cells occurred in a polar fashion, most likely at the epithelial luminal surface. Serial immunoelectron micrographs showed evidence of membrane fusion with pedestal formation between the gonococcus and the epithelial cell, gonococci within vacuoles, and occasional gonococci free in the cytoplasm. Immunoelectron microscopy studies showed ruptured vacuoles at the cell surface releasing organisms. These studies demonstrate that urethral epithelial cells are invaded by gonococci during the course of infection in males.     

Concentrations and bioavailability of cadmium and lead in cocoa powder and related products.

Concentrations and bioavailability of cadmium (Cd) and lead (Pb) were determined in cocoa powders and related products (beans, liquor, butter) of different geographical origins. Particular attention was paid to the fractionation of these metals, which was investigated by determining the metal fraction soluble in extractant solutions acting selectively with regard to the different classes of ligands. The targeted classes of Cd and Pb species included: water-soluble compounds, polypeptide and polysaccharide complexes, and compounds soluble in simulated gastrointestinal conditions. The bioavailability of Cd and Pb from cocoa powder, liquor and butter was evaluated using a sequential enzymolysis approach. The data obtained as a function of the geographical origin of the samples indicated strong differences not only in terms of the total Cd and Pb concentrations, but also with regard to the bioavailability of these metals. The Cd concentrations in the cocoa powders varied from 94 to 1833 microg kg(-1), of which 10-50% was potentially bioavailable. The bioavailability of Pb was generally below 10% and the concentrations measured in the cocoa powders were in the 11-769 microg kg(-1) range. Virtually all the Cd and most of Pb were found in the cocoa powder after the pressing of the liquor.