A Fast Buckling Analysis of Statically Indeterminate Variable-Section Struts

The force method, together with the virtual work principle, is used on desktop computers for the buckling analysis of variable-section struts. The method is based on the direct integration of the internal-work integral. The method is applied to struts composed of a thicker midsection and of two thin endsections under axial load. Several different upper-end constraints are considered. Such struts are used in fusion technology and in the cryogenic industry as flexible supports. Analyses appropriate to the flexible support of the toroidal field coils and of the vacuum vessel for the Next European Torus (NET) Project for the Controlled Thermonuclear Fusion Research are shown as examples.     

Effects of Lactobacillus rhamnosus GG addition in ice cream

A 2⁴ full factorial experimental design was applied to verify the effects of Lactobacillus rhamnosus GG (LGG) addition in retail-manufactured ice cream stored at two different freezing temperatures (−16°C and −28°C) and containing two different levels of sugar (15–22%) and fat (5–10%). In addition to microbial counts, the pH, acidity, viscosity of the mixes and functional properties of the ice creams were evaluated. Both fresh and frozen-thawed LGG cells underwent preliminary resistance tests to bile, antibiotics and acidity. The LGG strain proved to be highly resistant to most of the stress factors. When the micro-organism was added to ice cream mixes in a quantity of 10⁸ cfu/g, it did not change the overrun, firmness or melting behaviour of the finished product. Regardless of formulation, no count decay of LGG cells was observed in ice cream stored for up to 1 year.     

Water Vapor Resistance of Red Delicious Apples and Celery Sticks Coated with Edible Caseinate-Acetylated Monoglyceride Films

An optimal caseinate-acetylated monoglyceride edible coating consisting of 1.5% Alanate-310 (a calcium caseinate) and 1.5% Myvacet-5-07 (an acetylated monoglyceride) produced a reduction (75%) in moisture loss from celery (Apium graveolens) sticks. Similar edible coatings on apple (Malus domestica) fruits produced higher water vapor resistance. However, since apples have a natural high resistance to water vapor, edible coatings did not decrease water loss from whole fruit. Edible coatings did not modify respiration or ethylene production by apples or celery sticks. Quality of minimally processed fruits and vegetables that are susceptible to water loss could be improved with edible coatings, but quality of commodities with high water vapor resistance would not.     

Near Infrared Spectrophotometric Determination of Individual Sugars in Aqueous Mixtures

Near infrared region (NIR) spectrophotometry was used to determine concentrations of glucose, fructose and sucrose in aqueous mixtures at 10, 25, and 40% total sugars. Calibration equations and predicted individual concentrations in each total sugar level are reported. The standard errors of prediction varied between 0.35 and 0.69 and confidence limits ranged from ± 0.7 to ± 1.1%. In developing a single equation for predicting individual sugars in solutions, suitable for use over a range of total sugar concentrations, spectral data needed correction for sample density differences. However, at total sugar concentrations above 25%, accompanying wavelength shifts were of sufficient magnitude that a satisfactory single equation could not be developed. Equations for predicting individual sugars in solutions ranging from 10–25% total sugar concentrations were developed. For higher values of total sugars, appropriate calibrations were necessary.     

Performance of a Scraped-Surface Heat Exchanger Under Ultra High Temperature Conditions: A Dimensional Analysis

Performance characteristics of a pilot-scale scraped-surface heat exchanger (Contherm Model 6 × 2) under UHT operating conditions were evaluated. Outlet temperature and overall heat transfer coefficient (U) were significantly affected by rotational speed of the blades, mass flow rate of feed, feed inlet temperature, steam pressure and solids content of the model low-acid liquid food (soy extracts). The scraping action of the blades greatly improved the performance up to about 350 rpm; higher blade speeds had little or no effect and sometimes decreased U values. Application of dimensionless models showed that the effect of axial Reynolds number (Re_A) on the Nusselt number was more significant in the turbulent regime (Re_A > 1800), while rotational Reynolds number above 10⁵ had a significant effect at all values of Re_A between 1200 and 3700. At very high values of the Taylor number (> 10¹⁰) when laminar axial flow conditions prevailed, Nusselt number decreased with increase in rotational Reynolds number.     

Review: Kinetic parameters for thiamine degradation in foods and model solutions of high water activity

Literature data for the rates of thiamine destruction in a wide variety of model systems, buffer solutions and foods have been used to determine the kinetics of thiamine destruction during processing. A range of conditions, including temperature, pH, oxygen and catalysts indicate that, in most cases, the destruction of thiamine follows first order reaction kinetics. When information is limited, these calculations may be used to extrapolate data and predict modifications of processing to minimize losses of thiamine.     

Adaptive checkpointing in message passing distributed systems

Determining consistent global checkpoints is common to many distributed problems such as fault-tolerance, distributed debugging, properties detection, etc. Uncoordinated and coordinated checkpointing algorithms have been traditionally used for such determinations. This paper addresses a third technique, namely adaptive checkpointing, that has recently emerged. This technique assumes processes take local checkpoints independently and requires them to take additional local checkpoints in order that all local checkpoints be members of some consistent global checkpoint. We first study the characteristics of such adaptive algorithms. Then, a general adaptive checkpointing algorithm is designed from a condition, first stated by Netzer and Xu, that answers the following question: ‘does a given local checkpoint belong to a consistent global checkpoint’' (such a local checkpoint is not useless). The resulting algorithm has the nice property to reduce the number of additional local checkpoints taken to ensure the property ‘no local checkpoint is useless’. Futhermore, it provides each local checkpoint with a consistent global checkpoint to which it belongs. Compared to uncoordinated and coordinated checkpointing algorithms, this algorithm combines the advantages of both without inheriting their drawbacks.     

AN EFFICIENT DNA-EXTRACTION PROTOCOL FOR NUT SEEDS

Establishing genetic origin of food products allows verification of the authenticity of valuable foods and discourages adulteration with material of lower cost and value. This is particularly important for food products that have obtained European recognition. The use of molecular markers could be a solution for species and cultivar identification and for the genetic traceability. The development of efficient DNA-extraction protocols is an essential step for the procedure. In this work, a method for total DNA isolation was developed for hazelnut, almond and walnut seeds. The efficiency and reliability of the method was tested by assessing quantity and quality of the extracted DNA, and by Polymerase Chain Reaction (PCR) amplification, using two decamer primers and three universal primer pairs designed on the chloroplast DNA. The success of amplifications confirmed the presence of both nuclear and chloroplast DNA in the extracted sample.

PRACTICAL APPLICATIONS

Cultivar identification of nuts, based on morphological traits only, is often difficult, and adulterations with seeds of lower cost and quality are easy, above all when they are sold as shelled kernel, as is common for hazelnut. The genetic identification of cultivars is nowadays a routine practice, because of the development of DNA-typing techniques based on molecular markers. An efficient DNA-extraction procedure for hazelnut, almond and walnut seeds is a preliminary step required for enabling the recognition of the cultivar of origin of the nuts and fighting commercial frauds. It will also be useful in marker-assisted selection, applied in breeding.     

PURIFICATION AND CHARACTERIZATION OF THREEISOZYMES OF PECTIN METHYLESTERASE FROM TOMATO FRUIT

Three isozymes of pectin methylesterase (EC 3.1.1.11) have been purified to homogeneity from tomato (var. S. marzano). The isozymes were separated by affinity chromatography on Heparin-Sepharose column. They exhibited a molecular mass of 31 kDa when analyzed in sodium dodecyl sulfate gel electrophoresis and of 35 kDa in gel-filtration chromatography in native conditions. The isoelectric points of all three isozymes were found to be higher than 9.3. The K_ms calculated for the three isozymes were different toward citrus pectin used as substrate; one had a K_m of 9.7 mM (by expressing the pectin concentration as mmoles/L of methoxy groups) and the other two had similar K_ms of 3.0 and 2.6 mM, respectively. The isozyme having the higher K_m for substrate was inhibited by citrus pectin (which had a degree of methylation of 70%) at concentrations higher than 5 mM, but no inhibition was found using a pectin with a degree of methylation of 30% at concentrations up to 13 mM (i.e. 9 mg/ml) with a K_m of 14.7 mM. Furthermore, this isozyme showed a more broad range of activity in a pH range 5–10 with respect to that exhibited by the other two isozymes. All three isozymes were found to be glycosylated, although to different extents.