Carbon aerogel spheres prepared via alcohol supercritical drying

We have developed a method that would allow for the fabrication of carbon aerogel (CA) spheres. The inverse phase suspension polymerization of resorcinol and formaldehyde monomers with Na₂CO₃ as a catalyst followed by supercritical drying was explored. The effects of the chemical formulation and processing procedures and the conditions of the structures of organic and related carbon aerogels were studied. The experimental results indicated that it was easy to avoid the accumulation of polymerization heat during gelation, and easy to take out the products from the reaction container, through this fabrication method. Sol-gel microspheres with diameters ranging from about 30-1000μm could be obtained. After drying the sol-gel spheres under alcohol supercritical drying conditions, aerogel spheres with a bulk density of 0.8-1.0 g/cm³were prepared, and by subsequently pyrolyzing them, CA spheres with surface areas of 250-650 m²/g were obtained. The resultant CA spheres could be used as the electrode materials of supercapacitors. The specific capacitance of the CA spheres was as high as 215 F/g, and the equivalent series resistance at 48 Hz was about 1 Ω.     

Physico-chemical and Sensory Characteristics of Flavored Snacks from Extruded Cassava/Pigeonpea Flour

ABSTRACT: The effects of pigeonpea flour (PF) addition to cassava flour (CF) on the sensory and physico‐chemical quality of extrudates were investigated. Products with added PF were more yellow, had higher protein, bulk density, and water absorption index with lower expansion and water absorption index. Extrudate with 95% CF/5% PF had a suitable crisp to hard texture. All enrobed products were liked moderately to very much in overall acceptability. Chocolate extrudates were most liked (p < 0.01) for flavor and color over paprika, hickory, and cheese/onion.     

X‐Ray Spectroscopic Investigation of Chlorinated Graphene: Surface Structure and Electronic Effects

Chemical doping of graphene represents a powerful means of tailoring its electronic properties. Synchrotron‐based X‐ray spectroscopy offers an effective route to investigate the surface electronic and chemical states of functionalizing dopants. In this work, a suite of X‐ray techniques is used, including near edge X‐ray absorption fine structure spectroscopy, X‐ray photoemission spectroscopy, and photoemission threshold measurements, to systematically study plasma‐based chlorinated graphene on different substrates, with special focus on its dopant concentration, surface binding energy, bonding configuration, and work function shift. Detailed spectroscopic evidence of C–Cl bond formation at the surface of single layer graphene and correlation of the magnitude of p‐type doping with the surface coverage of adsorbed chlorine is demonstrated for the first time. It is shown that the chlorination process is a highly nonintrusive doping technology, which can effectively produce strongly p‐doped graphene with the 2D nature and long‐range periodicity of the electronic structure of graphene intact. The measurements also reveal that the interaction between graphene and chlorine atoms shows strong substrate effects in terms of both surface coverage and work function shift.     

A physicist's perspectives on the complementary roles of the physical and behavioral sciences.

Discusses issues faced by scientists and by science and technology and ways in which psychologists and other social scientists can aid the process of resolving these issues. One such area is the need for greater attention to education in mathematics and sciences, by both teachers and students; psychologists must work with educators and administrators in the implementation of programs designed to meet the demands posed by a world increasingly dependent on technology. In the same way, psychologists can address a number of socially oriented scientific issues, such as increasing minority and female participation in scientific professions, and in developing socially acceptable and viable approaches to problems in energy use, environmental preservation, and other areas. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Atomic nanotube welders: boron interstitials triggering connections in double-walled carbon nanotubes

Here we demonstrate that the incorporation of boron (B) atoms between double-walled carbon nanotubes (DWNTs) during thermal annealing (1400-1600 degrees C) results in covalent nanotube "Y" junctions, DWNT coalescence, and the formation of flattened multiwalled carbon nanotubes (MWNTs). These processes occur via the merging of adjacent tubes, which is triggered by B interstitial atoms. We observe that B atom interstitials between DWNTs are responsible for the rapid establishment of covalent connections between neighboring tubes (polymerization), thereby resulting in the fast annealing of the carbon cylinders with B atoms embedded in the newly created carbon nanotube network. Once B is in the lattice, tube faceting (polygonization) starts to occur, and the electronic properties are expected to change dramatically. Therefore, B atoms indeed act as atomic nanotube fusers (or welders), and this process could now be used in assembling novel electronic nanotube devices, nanotube networks, carbon nanofoams and heterojunctions exhibiting p-type electronic properties.     

Problem solving as a function of children's defensiveness and parental behavior.

The performance of 2 groups of 16 5th-grade boys, one low defensive and low anxious (LD) and the other high defensive and low anxious (HD) on the Defensiveness and Test Anxiety Scales for Children, was compared on the Porteus Maze Test taken with mothers absent and on a different form of the Porteus plus a jigsaw puzzle test with mothers present. Mothers were rated on a set of rating scales as they helped their sons with the puzzle. The results suggest that (a) discrepancies between ability and qualitative performance in defensive boys are a function of defensiveness whereas such discripancies in quantitative performance are a function of certain salient components of the test situation, and (b) communication is less effective in families of HD boys than in families of LD boys. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nanostructured Bulk Silicon as an Effective Thermoelectric Material

Thermoelectric power sources have consistently demonstrated their extraordinary reliability and longevity for deep space missions and small unattended terrestrial systems. However, more efficient bulk materials and practical devices are required to improve existing technology and expand into large‐scale waste heat recovery applications. Research has long focused on complex compounds that best combine the electrical properties of degenerate semiconductors with the low thermal conductivity of glassy materials. Recently it has been found that nanostructuring is an effective method to decouple electrical and thermal transport parameters. Dramatic reductions in the lattice thermal conductivity are achieved by nanostructuring bulk silicon with limited degradation in its electron mobility, leading to an unprecedented increase by a factor of 3.5 in its performance over that of the parent single‐crystal material. This makes nanostructured bulk (nano‐bulk) Si an effective high temperature thermoelectric material that performs at about 70% the level of state‐of‐the‐art Si_0.8Ge_0.2 but without the need for expensive and rare Ge.     

General deterrence effects of U.S. statutory DUI fine and jail penalties: long-term follow-up in 32 states

INTRODUCTION: We examined effects of state statutory changes in DUI fine or jail penalties for firsttime offenders from 1976 to 2002. METHODS: A quasi-experimental time-series design was used (n=324 monthly observations). Four outcome measures of drivers involved in alcohol-related fatal crashes are: single-vehicle nighttime, low BAC (0.01-0.07g/dl), medium BAC (0.08-0.14g/dl), high BAC (>/=0.15g/dl). All analyses of BAC outcomes included multiple imputation procedures for cases with missing data. Comparison series of non-alcohol-related crashes were included to efficiently control for effects of other factors. Statistical models include state-specific Box-Jenkins ARIMA models, and pooled general linear mixed models. RESULTS: Twenty-six states implemented mandatory minimum fine policies and 18 states implemented mandatory minimum jail penalties. Estimated effects varied widely from state to state. Using variance weighted meta-analysis methods to aggregate results across states, mandatory fine policies are associated with an average reduction in fatal crash involvement by drivers with BAC>/=0.08g/dl of 8% (averaging 13 per state per year). Mandatory minimum jail policies are associated with a decline in single-vehicle nighttime fatal crash involvement of 6% (averaging 5 per state per year), and a decline in low-BAC cases of 9% (averaging 3 per state per year). No significant effects were observed for the other outcome measures. CONCLUSIONS: The overall pattern of results suggests a possible effect of mandatory fine policies in some states, but little effect of mandatory jail policies.