Effect of Kraft Cooking Conditions on the Chemical Composition of the Surface and Bulk of Spruce Fibers

By varying cooking temperature, alkali charge, ionic strength, and cooking time in Kraft pulping of spruce chips, pulps ranging between kappa numbers 20–80 were obtained. The unbleached Kraft pulp fibers were subjected to mechanical peeling in order to separate the surface material from the bulk of the fibers and the carbohydrate composition and lignin content of the two fractions were analyzed. As expected, the lignin and xylan contents were higher on the fiber surface than in the fiber wall. The percentage of xylan on the fiber surface was fairly constant, independent of different pulping conditions or degree of delignification. The lignin proportion on the fiber surface gradually decreased with decreasing kappa number. At a given kappa number, pulping at a higher temperature resulted in less lignin on the fiber surface, probably because of the higher solubility of lignin at higher temperature. Cooking at lower alkali charge also resulted in lower lignin content on the fiber surface at a given kappa number. In this case, there was more time available for degradation of the surface lignin since the lower alkali charge resulted in longer cooking time needed to reach a certain kappa number.     

Postprandial and short-term effects of dietary virgin olive oil on oxidant/antioxidant status

It is generally believed that virgin olive oil consumption has beneficial effects, but little is known about its effects postprandially on oxidant/antioxidant status. The aim of this study was to determine changes in oxidative stress biomarkers and lipid profile after a single dose of virgin olive oil and after 1 wk of daily consumption. Sixteen subjects (9 men, 7 women) ingested 50 mL of virgin olive oil in a single dose. Blood samples were collected from 0 to 24 h. Thereafter, 14 participants (8 men, 6 women) followed a 1-wk 25 mg/d virgin olive oil dietary intervention. Blood samples were collected at the end of this period. Serum TAG (P=0.016), plasma FA (P<0.001) and lipid peroxidation products in plasma (P<0.001) and VLDL (P=0.007) increased, reaching a peak at 4–6 h, and returning to baseline values at 24 h after oil ingestion. The opposite changes were observed in plasma glutathione peroxidase (P=0.001) and glutathione reductase (GR) (P=0.042). No changes in LDL lipid peroxidation or resistance to oxidation were observed postprandially. At 24 h, plasma oleic acid remained increased (P<0.05) and resistance of LDL to oxidation improved (P<0.05). After 1 wk of virgin olive oil consumption, plasma oleic acid (P=0.031), resistance of LDL to oxidation (P<0.05), and plasma GR activity (P=0.005) increased. These results indicate that changes in oxidant/antioxidant status occur after oral virgin olive oil. Virgin olive oil consumption could provide short-term benefits for LDL resistance to oxidation and in glutathione-related enzyme activities.     

Porous silicon microcavities: synthesis, characterization, and application to photonic barcode devices

ABSTRACT: We have recently developed a new type of porous silicon we name as porous silicon colloids. They consist of almost perfect spherical silicon nanoparticles with a very smooth surface, able to scatter (and also trap) light very efficiently in a large-span frequency range. Porous silicon colloids have unique properties because of the following: (a) they behave as optical microcavities with a high refractive index, and (b) the intrinsic photoluminescence (PL) emission is coupled to the optical modes of the microcavity resulting in a unique luminescence spectrum profile. The PL spectrum constitutes an optical fingerprint identifying each particle, with application for biosensing.In this paper, we review the synthesis of silicon colloids for developing porous nanoparticles. We also report on the optical properties with special emphasis in the PL emission of porous silicon microcavities. Finally, we present the photonic barcode concept.     

Psychosocial Factors, Gender, and Sleep.

Low social support may contribute to poor sleep, more so than adverse aspects of demand and control and more so for women than men. This study on 1,179 working individuals, 623 women and 556 men, from the Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) study investigated the association between sleep and psychosocial factors. Chi-square analyses investigated the associations among sleep and demand, control, social networks, and emotional support. A logit log-linear model analyzed interactions. More women reported poorer sleep when perceiving adverse psychosocial factors. Interactive effects were found between adverse scores on demand, control, and emotional support. A multivariate partial least square analysis showed that poorer health, pain, and adverse aspects of emotional support and social networks contributed significantly to the pattern of poor sleep. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exploring gender and change

Changing Women, Unchanged Men? Sara Delamont, 2001 Buckingham: Open University Press. 128pp., ISBN 0 335 20037 0(paperback), £15.99     

Tribological behaviour of an elastomer aged in different oils

This paper presents the influence of aging the nitrile rubber, the most popular seal material, in various base fluids on sliding friction and abrasive wear. The lubricants used are synthetic esters, natural esters, different types of mineral base oils, poly-α-olefins and very high viscosity index oils. Friction has been studied for two directions of motion with respect to lay on the elastomer sample by using the SRV Optimol test machine. These findings show that as compared to all other lubricant formulations, ageing the elastomer in polyol ester leads to the maximum reduction of friction coefficient especially in perpendicular sliding to the initial lay on the surface. The abrasive wear studies were carried out by using a two-body abrasive wear tester against dry and lubricated elastomer. It was interesting to note that two-body abrasive wear of elastomeric material was higher during rubbing in presence of the fluids as compared to that in dry condition. Further, aging the elastomer in these base fluids especially in ester base fluids, results in more abrasive wear.     

Arachidonic acid biosynthesis in non-stimulated and adrenocorticotropin-stimulated sertoli and leydig cells

The biosynthesis of arachidonic acid in Sertoli and Leydig cells isolated from the testes of mature rats has been investigated. Both types of cells incorporated [2-¹⁴C]eicosatrienoic acid from the incubation medium and transformed it into arachidonic acid. The administration of adrenocorticotropin (ACTH) to the rats decreased the Δ5 desaturating activity in the isolated testicular cells, while ACTH produced no changes in the uptake of the substrate. Similar results were obtained when ACTH was added to the incubation medium of cells isolated from non-hormone treated rats. The total fatty acid composition of the Sertoli cells isolated from ACTH-treated rats showed a significant increase in the relative percentage of 18∶2n−6 and a decrease in the C₂₀ and C₂₂ polyenes. This may indicate that ACTH exerts an inhibitory effect on Δ6, Δ5 and Δ4 desaturase activities. Addition of corticosterone to the incubation medium also produced a significant decrease in arachidonic acid biosynthesis. Because ACTH is known to stimulate the release of corticosteronein vivo, both hormones may act cumulatively in the regulation of arachidonic acid metabolism in Sertoli and Leydig cells.     

Thermoelectric properties of thin films of bismuth telluride electrochemically deposited on stainless steel substrates

Bismuth telluride thin films have been synthesized by electrochemical deposition onto stainless steel substrates from acidic solutions. The influence of deposition variables on film composition, morphology and crystal orientation associated with the growth of the film was investigated by means of constant potential deposition and pulsed potential deposition. In-plane thermoelectric and transport properties of the electrodeposited films were measured. The carrier concentration of the electrodeposited films was found to be one order of magnitude larger than typically reported for optimized bulk bismuth telluride, which explains the unusually low Hall mobility and Seebeck coefficient values found for the electrodeposited films. Pulse deposited films showed slightly lower electrical resistivity and higher Seebeck coefficient due to the lower porosity and less preferred crystal orientation of the films compared to the continuously deposited films. Improvements of the film properties are necessary to make them viable for applications.     

Optical angular correlation in fourier domain

Abstract

The angular correlation of Fourier spectra is optically implemented by means of a single Fourier transformer. Fourier-domain-based angular correlation, which is a technique specific to periodic pattern recognition and characterization, is efficiently applied in real time to ordinary textile structures. By introducing scale corrections, either isomorphic or anamorphic, the optical system is capable of recognizing different structures of the same sort of fabric even when the fundamental frequencies—or thread densities—do not coincide. Two possible methods to introduce the information into the input image of the optical angular correlator are considered: an opto-mechanical rotator containing a transparency with the input sample image; and an electronic addressed spatial light modulator that displays the input sample image controlled by computer. Experimental results of both possibilities are presented and discussed.