A CIRCULAR-DICHROISM STUDY OF THE ENTEROTOXIN FROM CLOSTRIDIUM PERFRINGENS TYPE A

Far-UV circular-dichroism spectra of the enterotoxin from Clostridium perfringens type A were recorded under different conditions, and conformational analysis was performed. The native enterotoxin (pH 6.8) was shown to contain about 80% pleated sheet, 20% random coil and no helix structure. By adding small amounts of the detergent sodium dodecyl sulfate (0–261 mol SDS/mol enterotoxin), the β-sheet structure could gradually be changed to a more α-helical structure. Treatment with 8 M urea resulted in limited alterations of the secondary structure of the enterotoxin, while heat treatment (60°C, 30 min), treatment with 6.5 M guanidine hydrochloride or 0.01 M NaOH led to a dramatic increase in the amount of random coil.     

Direct-Current Conductivity of Y2O3 as a Function of Water Vapor Pressure

The dc conductivity of a sintered sample of Y₂O₃ containing an excess of lower-valent metal (Ml) impurities has been measured at 600° to 1100°C in air as a function of the water vapor pressure (0.4 to 3000 Pa). The logarithm of the p -type conductivity vs log P _H2o has a slope of – 1/2 in certain regions of F _H2o and temperature. This reflects a defect situation where interstitial protons from water vapor balance the excess of lower-valent cation impurities: [H_˙] = [M1_']. The activation energy for the p -type conductivity under these conditions is evaluated and interpreted in terms of the enthalpy needed to dissolve interstitial protons in yttria.     

Eigenstructure and residuals in multivariable state-feedback design

In this paper it is shown that all residuals assignable by state feedback must belong to certain well-defined subspaces defined by the freely selectable closed-loop eigenvalues. These subspaces are straightforward to compute, and the computational requirements are modest. The applicability of this result is facilitated by the fact that fundamental control design objectives like I/O response and robustness can be expressed in terms of residuals. A design procedure is outlined and illustrated by an example. The method is applicable to square and non-square systems.     

Quantification of the 3D microstructure of SC surfaces

This study presents the development of an ImageJ plugin for surface characterization. Based on gradient analysis, parameters, such as the gradient magnitude, orientation, mean resultant vector and surface area are derived. A comparative study of supercalendered (SC) papers was performed to verify the surface representations yielded by a laser profilometer. The surface representations of samples covered with carbon and gold were compared to untreated samples. The results confirm the suitability of gold coating for reducing the artefacts encountered on laser profilometry surface representations of paper. In addition, a complete scanning electron microscopy analysis is performed on the assessed samples to quantify the surface fraction covered by mineral fillers and to reveal the true 3D microstructure of SC surfaces. The influence of filler coverage and filler type on the gloss level of commercial SC papers is evaluated. The relationship between the surface topography, gloss and PPS roughness for a series of commercial SC papers is established.     

COMMENTS ON THE ARTICLE BY DAVID L. WOLITZKY: "EFFECT OF FOOD DEPRIVATION ON PERCEPTION-COGNITION: A COMMENT."

WOLITZKY (SEE 42:1) SEEMS TO HAVE MISUNDERSTOOD SAUGSTAD'S STATEMENTS CONCERNING THE DEFINITION OF HUNGER AND THE NATURE OF THE ASSOCIATION TESTS PRODUCING AN EFFECT. HE HAS ALSO BASED HIS ARGUMENT ON WORK OF A PRELIMINARY NATURE. HIS STATEMENT CONCERNING THE EFFECT OF AMBIGUOUS MATERIAL HAS NO CLEAR SUPPORT IN THE EXPERIMENTAL LITERATURE, AND THERE IS LITTLE EVIDENCE THAT TASKS REQUIRING AN ACCURATE RESPONSE MAY REVEAL A DEPRIVATION EFFECT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

AROMA COMPOUNDS AS MARKERS OF WINE QUALITY IN THE CASE OF MALVAZIJA ISTARSKA YOUNG WINE

ABSTRACT

In order to investigate the relationship between sensory and gas chromatographic analysis data, and to establish if particular aroma compounds could be used as Malvazija istarska young wine quality markers, 30 samples of Malvazija istarska young wine were subjected to sensory evaluation and gas chromatographic analysis of aroma compounds. Linear regression and principal component analysis were applied in order to establish the relations between sensory evaluation scores and aroma compound concentrations in corresponding wines. The most important contributors to the characterization and differentiation of wines evaluated with higher sensory evaluation scores were isoamyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, hexanoic acid, octanoic acid and decanoic acid. On the other hand, wines evaluated with lower sensory evaluation scores were characterized and differentiated by higher amounts of isoamyl alcohol and isobutanol. Mentioned esters and acids were also found to be the most important variables for the classification of these wines according to quality using stepwise linear discriminant analysis (SLDA). The evaluation of the SLDA model was performed by cross‐validation, obtaining an average percentage of correct classification of 100.0%, and of correct prediction of 89.3%. The results of this investigation suggest that above‐mentioned esters, acids and alcohols could be used as markers of Malvazija istarska young wine quality.

PRACTICAL APPLICATIONS

Wine aroma is one of the most important parameters responsible for its quality, and hence for consumer acceptance. Sensory evaluation is the most common technique for controlling the organoleptic quality of wine, but it is not always feasible, since it requires specific conditions, and a group of trained expert tasters that can only assess a relatively small number of wine samples for a day. Moreover, the subjectivity of panelists can affect the evaluation in a great measure. The approach proposed in this work suggests the use of a nonsubjective instrumental technique such as gas chromatography for the analysis of volatile aroma compounds as a complementary tool for wine quality control able to predict, confirm or to correct the results of Malvazija istarska young wine sensory evaluation. Although this model is yet far from being practically implemented, information obtained could be used as a starting ground. Moreover, it was assumed that the approach proposed in this work is likely to be applied successfully on the differentiation and classification of other types of wine according to quality.     

Phase Formation in the System Na2O · Al2O3-CaO · A12O3-Al2O3 at 1200°C in Air

Phase relations in the system Na₂O_· Al₂O₃-CaO· Al₂O₃-Al₂O₃ at 1200°C in air were determined using the quenching method and high-temperature X-ray diffraction. The compound 2Na₂O · 3CaO · 5Al₂O₃, known from the literature, was reformulated as Na₂O · CaO · 2Al₂O₃. A new compound with the probable composition Na₂O · 3CaO · 8Al₂O₃ was found. Cell parameters of both compounds were determined. The compound Na₂O · CaO-2Al₂O₃ is tetragonal with a = 1.04348(24) and c = 0.72539(31) nm; it forms solid solutions with Na₂O · Al₂O₃ up to 38 mol% Na₂O at 1200°C. The compound Na₂O · 3CaO · 8Al₂O₃ is hexagonal with) a = 0.98436(4) and c = 0.69415(4) nm. The compound CaO · 6Al₂O₃ is not initially formed from oxide components at 1200°C but behaves as an equilibrium phase when it is formed separately at higher temperatures. The very slow transformation kinetics between β and β "-Al₂O₃ make it very difficult to determine equilibrium phase relations in the high-Al₂O₃ part of the diagram. Conclusions as to lifetime processes in high-pressure sodium discharge lamps can be drawn from the phase diagram.     

Strategic decisions in manufacturing— on the choice of investments in flexible production organizations†

The striving for market-oriented production has resulted in increased needs for flexibility in the production process. In many cases it is the final value-adding component (i.e. assembly) in the manufacturing chain that has the largest pressures for flexibility. However, the internal and external vendors can restrict the flexibility of a nominally flexible assembly plant. Without the necessary flexibility in earlier production stages a total flexibility will only be achieved through large inventories and other trade-offs. In this paper based on an empirical study carried out in cooperation with a large Swedish manufacturer, the authors show that total flexibility in a multi-stage production chain primarily depends on capacity levels and work organization. It is concluded in the case presented here that large investments must be made in labour education and organizational adaptation in order to exploit the full potentials of a highly mechanized final assembly department     

Original Golden Hit. An Essay Review

I. Bernard Cohen, Introduction to Newton's Principia . Cambridge: at the University Press, 1971.
Isaac Newton's Philosophiae naturalis principia mathematica. The third edition (1726) with variant readings. Assembled and edited by Alexandre Koyré and I. Bernard Cohen with the assistance of Anne Whitman. 2 vols. Cambridge: at the University Press, 1972.