Preparation of sections of plastics and polymers for the electron microscope

Experimental details of a method for sectioning rubbers and plastics at room temperature are presented. Usually specimens are embedded in a butyl-isobutyl methacrylate mixture (provided that they do not dissolve in the monomer) which can be polymerised by ultra-violet light to varying hardness. This enables sections through fibres and surfaces to be obtained. Because of distortion of the surface layers the angle between the knife and specimen is critical. The thickness of these distorted surface layers rather than the total thickness of the specimen provides a limit to the resolution obtained. Choice of the sectioning angle was made primarily by means of sense of touch, so that a microtome design incorporating a direct transmission of pressure from specimen to hand is needed.     

Family interaction as antecedent to the direction of male aggressiveness.

In a longitudinal study of antisocial aggressiveness in males, reports on direct observation of behavior in childhood and early adolescence were used to rate general level of aggressiveness. Criminal records were used to ascertain antisocial behavior during adolescence and adulthood. To distinguish between conditions which contribute to socialized aggressiveness and those which direct aggression into antisocial channels, the family backgrounds of men who had been equally aggressive in childhood were compared. The results suggest that extreme neglect and punitiveness, coupled with a deviant-aggressive paternal model produces antisocial aggressiveness. In contrast (thought not contradiction), moderate neglect, moderate punitiveness, and ineffective controls produce socialized aggressiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A multivariate study of attention dysfunction in schizophrenia.

Administered 5 tests purported to measure attention dysfunction to 60 schizophrenic and 60 nonschizophrenic male psychiatric patients. There was 30 chronic and 30 acute Ss in each group. The measures used were: size estimation, reaction time, and vigilance tasks, the Goldstein-Scheerer Object Sorting Test, and a proverb-interpretation task. Contrary to previous assumptions, these tests did not intercorrelate highly. In addition, individual-difference variables, as measured by staff ratings on the Psychotic Reaction Profile, failed to correlate significantly with task performance. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A consideration of methods of determining the radiative characteristics of jet fires

The radiative characteristics of jet fires is usually expressed through the use of a fraction of heat radiated, which is primarily a property of the fuel being considered. It is generally determined from experimental data of incident radiation around a fire and then derived by using a model of the incident radiation in terms of the fraction of heat radiated. Popular approaches include the single point source model where the flame is represented by a single point usually located halfway along the flame, or use of an idealised flame shape, such as a cylinder or cone, and deriving the flame surface emissive power which is closely related to the fraction of heat radiated. However, these modelling approaches may provide erroneous results for the fraction of heat radiated if incident radiation data in the near-field is used, and the fraction of heat radiated derived using one modelling approach may not be applicable to another approach without some adjustment. This paper explores the inherent near-field and far-field behaviour of different modelling approaches and the resulting impact on the fraction of heat radiated derived from each modelling approach using incident radiation data. A weighted multi-point source approach model was found to replicate both near-field and far-field behaviour well and capable of deriving the true fraction of heat radiated. Four idealised shapes were considered and it was found that the true fraction of heat radiated would need to be adjusted for use with these models even in the far-field, and some shortcomings in near-field behaviour were identified, which would suggest that some weighting of the surface emissive power over different regions of the flame would be needed. Finally, an idealised shape with hemispherical point sources distributed over its surface was considered and this model behaved well in both the near-field and far-field.     

Temperature and organic matter dependence of the distribution of organochlorine compounds in mountain soils from the subtropical Atlantic (Teide,Tenerife Island)

Surface soil samples from Teide mountain (Canary Islands) have been analyzed for polychlorobiphenyls (PCBs), DDTs, hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and pentachlorobenzene. The samples were situated between 10 and 3400 m above sea level being distributed below, at, and above the permanent inversion layer system characteristic of the subtropical Atlantic. All OC concentrations were, in general, low when compared with the data from urban, agricultural, or woodland soils reported elsewhere. Typical ranges were 0.04-9.2, 0.01-40, 0.001-1, or 0.01-3.2 ng x g(-1) dry weight for total PCBs, DDTs, HCHs, or HCB, respectively. These compounds exhibited a high dependence from the soil total organic carbon (TOC), showing high coefficients in the log(OC) versus log(TOC) correlations. The slopes of the curve fitted straight lines were, in turn, highly correlated to the log-transformed octanol-air coefficients of the compounds. This overall OC distribution points to steady-state conditions for the concentrations of these compounds in these mountain soils, in equilibrium with TOC. The equilibrium conditions are reached, despite the restrictions to convective air movement associated to the permanent atmospheric inversion layer at these latitudes. In addition, the log-transformed TOC-normalized concentrations of most PCBs, HCB, and pentachlorobenzene exhibit a good correlation with the reciprocal of average annual atmospheric temperatures also showing a temperature dependence for their distribution in the high mountain system. The calculated pseudo-enthalpies for this dependence, 120-160 kJ x mol(-1), exhibit higher values than those of octanol-air phase change calculated from laboratory experiments in previous studies, 66-93 kJ x mol(-1). The difference suggests a higher affinity of OC to soils than that corresponding to simple adsorption mechanisms.     

CuMnOx catalysts for internal reforming methanol fuel cells: Application aspects

The Internal Reforming Methanol Fuel Cell (IRMFC) incorporates a methanol reforming catalyst into the anodic compartment of a high temperature, polymer electrolyte membrane fuel cell (HT-PEMFC). The present work examines application aspects of the cell, including the operation temperature, the type of catalyst pretreatment, the effect of phosphoric acid leaching and the time-on-stream behavior of CuMnOx catalysts. Combustion-synthesized structured catalysts can efficiently operate at 200 °C with a 30% decline in MeOH conversion after 350 h on methanol/water stream in the presence of the high temperature polymer electrolyte membrane electrode assembly. Differences observed in the catalytic activity of oxidized versus prereduced samples with respect to phosphoric acid poisoning are negligible after long operation time.     

Phenolic compounds present in natural haze protein of Sauvignon white wine

Protein haze in white wines remains a problem for wineries. In addition to protein composition, many other factors have been identified that can participate in and even trigger the appearance of hazes. Phenolic compounds may be one of the non-protein factors involved in protein haze formation. The aim of this study was to identify and quantify the polyphenols present in the natural precipitate of a Sauvignon wine. The identification and quantification of polyphenols present in wine before and after natural precipitation and also in a natural precipitate were carried out by GC/MS and HPLC/ESI-TOF. The natural precipitate was also hydrolyzed in an acidic medium (Bate-Smith reaction). The results indicate that several phenolic compounds were present in the protein haze (tyrosol, trans-p-coumaric, trans-caffeic, vanillic, protocatechuic, syringic, gallic, ferulic, shikimic acids, (+)-catechin, ethyl coumaric acid ester and quercetin). Moreover, the detection of cyanidin after acid hydrolysis indicates the presence of procyanidins.     

Optimization of the operating conditions for steam reforming of slow pyrolysis oil over an activated biochar-supported Ni–Co catalyst

Highly performing activated biochar-based catalysts were produced for steam reforming of slow pyrolysis oil. The raw biochar obtained from the slow pyrolysis step was physically activated with CO₂ at 700 °C and 1.0 MPa and then employed as support. Preliminary tests on steam reforming of acetic acid at 600 °C showed that using activated biochar-supported catalysts containing 10 wt % Ni and 7 wt % Co led to a conversion above 90% with a relatively slow deactivation rate. When a representative organic model compounds mixture was used as feed, relatively fast deactivation of the catalyst was observed, probably due to the adsorption of heavy organic compounds, which could subsequently react to form not easily desorbable reaction intermediates. However, the dual Ni–Co catalysts exhibited a good performance during the steam reforming of a real slow pyrolysis oil at 750 °C, showing long stability and a constant carbon conversion of 65%.     

Anterior chamber parameters in early and advanced keratoconus. A meridian by meridian analysis

Purpose

To explore anterior segment changes with keratoconus onset and progression to determine whether structural changes are predominantly corneal, limbal or both. To investigate these changes in different corneal meridians.

Comparison of analytical methods for measuring proanthocyanidins in wines and their relationship with perceived astringency

The concentration of proanthocyanidins from twenty red wines from cv. Cabernet Sauvignon, five rosé wines from cv. Cabernet Sauvignon and five white wines from cv. Sauvignon Blanc was quantified using four analytical methodologies, and their relationship with the perceived astringency was investigated. Proanthocyanidin concentrations were determined by a methylcellulose precipitation assay, a protein precipitation assay and two colourimetric methods (Bate‐Smith and vanillin assay). The four methodologies showed high repeatability but differed widely in proanthocyanidin concentrations. The methylcellulose and protein precipitation assays could not quantify proanthocyanidins in rosé and white wines. The protein precipitation assay gave the lowest concentration of proanthocyanidins in all of the red wines. The methylcellulose precipitation assay (r = 0.7725; r² = 0.59) and the protein precipitation assay (r = 0.6828; r² = 0.47) showed a strong correlation with the perceived astringency compared with the colourimetric methods. The strong correlation of the methylcellulose precipitation method with the perceived astringency could be a useful tool to estimate red wine astringency.