Identification and analysis of 2-chloro-6-methylphenol, 2,6-dichlorophenol and indole: causes of taints and off-flavours in wines

Background and Aims: The aim of this study was to determine the cause of taints and off-flavours in a number of commercial wines and to develop methods for quantitative analysis of the compounds responsible. Methods and Results: Three compounds, 2-chloro-6-methylphenol (i.e. 6-chloro-ortho-cresol), 2,6-dichlorophenol and indole, were identified by gas chromatography (GC)/mass spectrometry (MS)/olfactometry as causes of taints or off-flavours in the wines. New methods for quantitative analysis of these three compounds, as well as some other chloro- and bromophenols were developed. The methods employed GC/MS and stable isotope dilution analysis, and confirmed the presence of 2-chloro-6-methylphenol, 2,6-dichlorophenol and indole in some wines at concentrations well above their odour and taste detection thresholds. Conclusions: 2-Chloro-6-methylphenol, 2,6-dichlorophenol and indole were confirmed as causes of taints and off-flavours in commercial wines. Significance of the Study: The development of new analytical methods will make it possible to determine whether chlorophenol (and perhaps also bromophenol) taint in wine is more widespread than previously recognised. Similarly, the simple, rapid and accurate method for quantifying indole in wine will allow large numbers of wine and ferment samples to be studied to determine those factors that can result in unacceptably high concentrations in commercial wines.     

Radiometric correction of SAR images A new correction algorithm

Abstract

Spatial variations of the backscatter coefficient result from synthetic aperture radar imaging systems and their platforms. An adaptive algorithm has been developed to correct the multiplicative variation of the backscatter in the longitudinal (parallel to flight line) and lateral (perpendicular to flight line) directions. The coefficient of variation along the parallel and lateral profiles, which consist of the means of the pixels along these lines perpendicular to the respective profiles, is constant. This implies that the radiometric variations are multiplicative. Because standard correction methods such as polynomial transfer functions give unsatisfactory results, an adaptive correction algorithm was developed to correct these images. The algorithm produces a transfer function by means of a filtering window which moves along the profile in what is essentially a moving mean procedure. However, the length of the window is automatically adjusted as a function of the variation of the profile. The adjustment is based on a calculation of the probability that values to be included or excluded from the window belong to the included population. The effects of the successive correction steps were monitored using several thematic test sites. The resultant images provide both increased quality and quantity of data without any degradation of the statistical properties of the data.     

PROBLEMS WITH CHAOTIC CRYPTOSYSTEMS

Matthews [1] has proposed a function based on chaos theory for generating sequences of random numbers to be used like a one-time pad. When implemented on digital computer systems, these functions must produce repeating cycles of values. The cycle length turns out to be unpredictable and often short. The function is not suitable for cryptographic use in the manner proposed by Matthews.     

PRELIMINARY STUDIES ON EXTRACTIVE PHENYLALANINE FERMENTATION WITH UNCHARGED POLYMERIC BEADS

Extractive fermentation was used for phenylalanine production to prevent the crystallization of phenylalanine during the fermentation. Instead of the conventionally used ion exchange resin, uncharged polystyrene beads (Amberlite XAD-16) were used to extract phenylalanine from the fermentation broth. The experimental results obtained using a baffled shake flask showed that phenylalanine was not produced when the beads were added at the same time as the inoculum. From the detailed studies, it was found that hydrophobic nutrients such as tyrosine and colored materials from the soybean hydrolysate adsorbed onto the beads as well as phenylalanine. In order to overcome this problem, the beads were gradually added during the course of the fermentation to minimize the adsorption of the hydrophobic medium components. Using the gradual addition of the polymeric beads during fermentation, an equivalent amount of phenylalanine was produced as compared to the control, and 40% of the phenylalanine produced was extracted during the fermentation. It was concluded that extractive fermentation using polymeric beads could be an effective way of preventing the crystallization of phenylalanine during fermentation.     

Exchange Rates and the International Trade in Metals: The Case of Copper

The role of exchange rates in determination of the competitiveness of a nation's mineral industry is important, controversial, and not generally well understood. This paper attempts to explain the mechanics of exchange rate calculations as related to mining costs, illustrate various surrogrates for more exact calculations, and highlight some of the perplexing and controversial policy questions in this area. This paper concentrates on one industry—primary copper. However, much of the material presented is more general and applicable to other metals. Further, the paper is directed to supply-side issues, as these are of particular interest in the case of copper.     

CONCENTRATION OF ONION JUICE VOLATILES BY REVERSE OSMOSIS AND ITS EFFECTS ON SUPERCRITICAL CO2 EXTRACTION

Supercritical carbon dioxide extraction of onion oil at moderate temperatures produces aproduct which is characteristic of the fresh flavor of onions. It was attempted to improve extraction efficiency by concentrating the onion juice by reverse osmosis prior to supercritical CO₂ extraction. Reverse osmosis was carried out for all combinations of 600, 700, and 800 psi feed pressure and 25 and 35C. The juice was concentrated to 18 ^oBtix and then subjected to supercritical CO₂ extraction. The effect of concentration on the extraction process was evaluated by comparing the yields of extracts from concentrated juice with that of single strength juice. Concentration of onion juice by reverse osmosis improved the efficiency of supercritical CO₂ extraction of onion oil and did not alter its characteristic fresh aroma.     

MODELING THE CONTEXT AND CONTINGENCY OF GENTRIFICATION

ABSTRACT: Recent criticisms of the coherence of theories of gentrification, the potential for its continued expansion in the 1990s, and methods for assessing its extent and significance have cast doubt on the utility of further research on the subject. This paper presents an empirical analysis of how gentrification altered the socioeconomic profile of the inner areas of four US cities between 1960 and 1990. Field surveys are conducted to delineate areas of visible housing reinvestment in Chicago, Milwaukee, Minneapolis-St. Paul, and Washington, DC. Stepwise discriminant analysis of tract-level census data indicates that the degree to which gentrification reverses the urban status gradient is mediated by the context in which the process occurs. While restricted in magnitude, gentrification inscribes remarkably similar changes in socioeconomic composition in different cities and signifies a new and distinct dimension of urban socio-spatial structure.     

Microstructure-property relationships in silicate-matrix composites

Electron microscopy and associated analytical spectroscopic techniques have been used to characterize interfaces in SiC-fibre/silicate-matrix composites. Interface structure, formed via reaction during hot-press fabrication, is a function of time, temperature, matrix composition and fibre type. Interfaces with Nicalon or Tyranno fibres vary from amorphous carbon in fine precipitated form to continuous graphitic layers. Interface behaviour in a stressed composite, and hence the matrix microcracking stress, is a sensitive function of microstructure. Interface debond and shear properties have been assessed using indent-based ‘push-down’ and ‘push-through’ tests using a specially developed instrument within a scanning electron microscope. This uses piezoload measurement and translation, and is capable of dynamic image recording of the indentation sequence. Interface micromechanical (indent) measurements have been correlated with structure and macromechanical response in bend testing for a range of fibre/matrix types, processing and post-processing thermal treatments. An example is also given of interfaces prepared by fibre precoating.     

FRESH–CUT SPINACH QUALITY AS INFLUENCED BY SPIN DRYING PARAMETERS

Abstract Response Surface Methodology was used to evaluate the effect of speed (0 to 1080 rpm) and operation time (1 to 9 min) of spin drying on the excess water remaining on washed, fresh–cut spinach, and microbial growth and sensory deterioration during storage of the spinach. The higher the centrifugal speed, the less water excess was present at a given time, centrifugal speed having a greater influence on water excess than operation time. The aerobic and psychrotrophic microbial counts were not affected by the drying conditions. By visual inspection of the contour plots, the region of minimum browning was obtained for centrifugal speeds between 700–750 rpm (equivalent to centrifugal forces from 65.8 to 75.5 G) and operation time from 5 to 5.5 min. Under these conditions, the water excess on the produce should range from 0.2 to 0.5%.     

A simple and efficient alternative to implementing systematic random sampling in stereological designs without a motorized microscope stage

When properly applied, stereology is a very robust and efficient method to quantify a variety of parameters from biological material. A common sampling strategy in stereology is systematic random sampling, which involves choosing a random sampling relevant objects start point outside the structure of interest, and sampling at sites that are placed at pre‐determined, equidistant intervals. This has proven to be a very efficient sampling strategy, and is used widely in stereological designs. At the microscopic level, this is most often achieved through the use of a motorized stage that facilitates the systematic random stepping across the structure of interest. Here, we report a simple, precise and cost‐effective software‐based alternative to accomplishing systematic random sampling under the microscope. We believe that this approach will facilitate the use of stereological designs that employ systematic random sampling in laboratories that lack the resources to acquire costly, fully automated systems.