OXALACETATE SYNTHESIS IN APPLES AND BANANAS AT LOW TEMPERATURES

¹⁴CO₂ was applied to apples and bananas that were stored at various temperatures and the incorporation of ¹⁴C into oxalacetate was determined. Apples that were susceptible to internal breakdown showed an initial decrease in incorporation as the storage temperature was reduced but incorporation then increased at temperatures below 10°C (Jonathan) or 5°C (Twenty Ounce). Apples that were not susceptible to breakdown (Delicious and Granny Smith) showed no incorporation at any temperature. Green bananas showed a minimum incorporation at 10°C but in ripe bananas, incorporation markedly increased at all temperatures less than 20°C. The respiration rate of the apple varieties at 20°C was found to be higher in fruit that were more susceptible to breakdown whereas at O°C the higher rates of respiration were from fruit less susceptible to the disorder.     

Visual exploration of high dimensional scalar functions

An important goal of scientific data analysis is to understand the behavior of a system or process based on a sample of the system. In many instances it is possible to observe both input parameters and system outputs, and characterize the system as a high-dimensional function. Such data sets arise, for instance, in large numerical simulations, as energy landscapes in optimization problems, or in the analysis of image data relating to biological or medical parameters. This paper proposes an approach to analyze and visualizing such data sets. The proposed method combines topological and geometric techniques to provide interactive visualizations of discretely sampled high-dimensional scalar fields. The method relies on a segmentation of the parameter space using an approximate Morse-Smale complex on the cloud of point samples. For each crystal of the Morse-Smale complex, a regression of the system parameters with respect to the output yields a curve in the parameter space. The result is a simplified geometric representation of the Morse-Smale complex in the high dimensional input domain. Finally, the geometric representation is embedded in 2D, using dimension reduction, to provide a visualization platform. The geometric properties of the regression curves enable the visualization of additional information about each crystal such as local and global shape, width, length, and sampling densities. The method is illustrated on several synthetic examples of two dimensional functions. Two use cases, using data sets from the UCI machine learning repository, demonstrate the utility of the proposed approach on real data. Finally, in collaboration with domain experts the proposed method is applied to two scientific challenges. The analysis of parameters of climate simulations and their relationship to predicted global energy flux and the concentrations of chemical species in a combustion simulation and their integration with temperature.     

An investigation into microwave bonding mechanisms via a study of silicon carbide and zirconia

It is known that the glassy grain-boundary phase present in low-purity aluminas has two primary functions during direct microwave bonding. Firstly, it increases the dielectric loss of the host ceramic, allowing heating to occur; secondly, the bonding mechanism itself has been found to be based on viscous flow of the glassy grain-boundary phase. However, some evidence has also been found for the bonding of individual grains where they come into direct contact across the join line. To investigate the role of grain-boundary phases further, the microwave bonding of two different grades of silicon carbide and one grain of zirconia has been studied. A single-mode resonant cavity operating at 2450 MHz was used for both studies. The temperature and axial pressure were varied and the bonding time was kept to a minimum. Analysis of the resultant bonds indicated that both reaction-bonded silicon carbide and partially stabilized zirconia could be successfully joined using microwave energy with bonding times typically 10 min or less. For reaction-bonded silicon carbide ceramics, the silicon grain-boundary phase softened at the bonding temperature, allowing the butting faces to be "glued" together. Unlike the glassy grain-boundary phase for alumina ceramics, the silicon phase did not allow grain motion but always formed a discrete and continuous layer at the interface, even under optimum joining conditions. The work with zirconia confirmed that it is possible to join ceramics without the presence of a substantial grain-boundary phase. The mechanism is thought to be either solid-state diffusion and/or grain-boundary sliding. © 1998 Kluwer Academic Publishers     

Treatment of male urethral strictures: is repeated dilation or internal urethrotomy useful?

PURPOSE: We evaluate the efficacy of repeated dilation or urethrotomy as treatment of male urethral strictures. MATERIALS AND METHODS: Between January 1991 and January 1994, 210 men with proved urethral strictures were prospectively randomized to undergo filiform dilation (106) or internal urethrotomy (104). Followup was scheduled at 3, 6, 9, 12, 24, 36 and 48 months. Dilation or internal urethrotomy was repeated at the first and second stricture recurrence. The Kaplan-Meier method was used to estimate survivor function for the treatment methods (survival time being the time to first stricture recurrence) and the log rank test was used to compare the efficacy of different treatments. RESULTS: Followup (mean 24 months, range 2 to 63) was available in 163 patients (78%). After a single dilation or urethrotomy not followed by re-stricturing at 3 months, the estimated stricture-free rate was 55 to 60% at 24 months and 50 to 60% at 48 months. After a second dilation or urethrotomy for stricture recurrence at 3 months the stricture-free rate was 30 to 50% at 24 months and 0 to 40% at 48 months. After a third dilation or urethrotomy for stricture recurrence at 3 and 6 months the stricture-free rate at 24 months was 0 (p <0.0001). CONCLUSIONS: Dilation and internal urethrotomy are useful in a select group (approximately 70% of all patients) who are stricture-free at 3 months, and of whom 50 to 60% will remain stricture-free up to 48 months. A second dilation or urethrotomy for early stricture recurrence (at 3 months) is of limited value in the short term (24 months) but of no value in the long term (48 months), whereas a third repeated dilation or urethrotomy is of no value.     

Variability associated with testing shelled corn for fumonisin

Variances associated with sampling, sample preparation, and analytical steps of a test procedure that measures fumonisin in shelled corn were estimated. The variance associated with each step of the test procedure increases with fumonisin concentration. Functional relationships between variance and fumonisin concentration were estimated by regression analysis. For each variance component, functional relationships were independent of fumonisin type (total, B1, B2, and B3 fumonisins). At 2 ppm, coefficients of variation associated with sampling (1.1 kg sample), sample preparation (Romer mill and 25 g subsample), and analysis are 16.6, 9.1, and 9.7%, respectively. The coefficient of variation associated with the total fumonisin test procedure was 45% and is about the same order of magnitude as that for measuring aflatoxin in shelled corn with a similar test procedure.     

Escher: A New Technology Transitioning Model

The Escher model relies on a mix of government and industry funding to identify cross-industry needs and select technologies for maturation and transitioning. The Escher organization serves as a thin layer of management to join end users and the research community in setting standards, directing users to available sites, using uniform community-established criteria to monitor software's effectiveness, and taking advantage of user feedback to identify bugs and other software problems. Additionally, we foresee that Escher increasingly provide a common meeting place where stakeholders can develop a roadmap for the future and discuss common concerns and needs in NESS evolution     

Decentralised detection of periodic encounter communities in opportunistic networks

We tackle the problem of individuals being able to self-detect the encounter communities within which they periodically occur. This has widespread applicability, not least for future communication systems where content can be locally shared via wireless opportunistic networking when devices carried by participants come into close range. In this paper, we introduce a comprehensive model and decentralised algorithm to accomplish the detection of periodic communities in opportunistic networks. To the best of our knowledge, this is the first decentralised algorithm for the detection of periodic communities. We investigate the behaviour of our approach both analytically and with real-world data.     

Pigment Yellow G583-a misclassified pigment and its relationship with other acetoacetanilide azo pigments

Pigment Yellow G583 (nominally C.I. Pigment Yellow 6) has been compared with another version of C.I. Pigment Yellow 6 (Recolite Fast Yellow 3G) and the colour and the X-ray powder diffraction pattern have been found to be different. Density measurements, crystal structure analysis and chemical analysis have shown that the former is a mixed crystal of60 mol% C.I. Pigment Yellow 6 and 40 mol% C.I. Pigment Yellow 5. Pigment Yellow G583 was then compared crystallographically with a series of similar pigments, and it has been concluded that the structure of C.I. Pigment Yellow 6 is different to that of all the others. Regardless of composition, Pigment Yellow G583 is a mixed crystal of C.I. Pigment Yellow6 molecules in an α-C.I. Pigment Yellow 5 lattice and not vice versa. This does not necessarily make Pigment Yellow G583 a poor pigment, but a change of composition may cause the crystal lattice to become that of C.I. Pigment Yellow 6, changing the physical properties. The only way in which a change of crystal structure can be detected is to examine the X-ray diffraction pattern.     

Production,partial purification and properties of β‐mannanases obtained by solid substrate fermentation of spent soluble coffee wastes and copra paste using Aspergillus oryzae and Aspergillus niger

In order to achieve a higher added value of two galactomannan‐containing wastes, copra paste and spent coffee from the soluble coffee industry (SCW), solid substrate fermentation (SSF) was used. Filamentous fungi Aspergillus oryzae and A niger were used to evaluate the feasibility of producing β‐mannanase by SSF. A 2³ factorial design was used to select the best interaction among the two fungi, the two substrates and two fermentation times. The treatment ‘A niger–copra–2.5 days’ produced a significantly higher (p < 0.05) β‐mannanase activity, having five different isoforms of the enzyme, one of which was partially purified to a specific activity of 764 U mg⁻¹ (U = nmol of mannose released per second from a galactomannan substrate). Copra paste had a higher mannose/galactose ratio (14:1) than SCW (6:1), and low oil content, which led to higher β‐mannanase production from SSF. A β‐mannanase from SSF of copra produced by A oryzae was highly purified using acetone precipitation and cation exchange and size exclusion chromatographies. This enzyme had an MW of 110 kDa, a pI between 3.5 and 4.5 and a specific activity of 1760 U mg⁻¹; purification achieved was 90.7 times. The temperature and pH for optimal activity were 40 °C and 6.0 respectively. The optimal temperature was lower and the optimal pH higher than others previously reported (produced by submerged fermentation), which could be important for viscosity reduction of concentrated coffee extract in instant coffee manufacture. Copra is an interesting alternative for β‐mannanase production, since it is readily available in Mexico; moreover, the residue after SSF has a reduced galactomannan content and may be used for monogastric animal feed. © 2000 Society of Chemical Industry     

Variability associated with testing corn for aflatoxin

The sampling, subsampling (both coarse and fine ground meal), and analytical variances associated with testing shelled corn for aflatoxin were estimated by the use of 500 g samples, 50 g subsamples, and the CB method of analysis. The magnitudes of the variance components increased with an increase in the aflatoxin concentration. Functional relationships were developed to predict the variance for a given aflatoxin concentration and any size sample, subsample, and number of analyses. At 20 ppb total aflatoxin, the coefficient of variantion associated with a 4.54 kg sample, 1 kg subsample of coarsely ground meal (passes a #14 screen), a 50 g subsample of finely ground meal (passes a #20 screen) and one analysis were 21, 8, 11, and 26%, respectively.