MODELLING THE MECHANICAL AND HISTOLOGICAL PROPERTIES OF CARROT TISSUE DURING COOKING IN RELATION TO TEXTURE AND CELL WALL CHANGES

A tensile test was used to measure four mechanical properties of carrot tissue cooked under various time-temperature conditions. A kinetic model describing the changes of these mechanical properties measured during cooking was developed. The histological properties of the rupture surfaces caused by the mechanical testing were investigated. The kinetic model was found capable of predicting the changes in the rupture mechanism of the cell walls. Determining the percentage of cell wall ruptures proved to be an accurate method to assess the textural state of carrot tissue during cooking as compared to the measurement of the mechanical properties.     

VIRULENCE LEVELS OF BIOFILM-GROWN LISTERIA MONOCYTOGENES LO28 ARE LOWER THAN THOSE OF PLANKTONIC CELLS IN AN ORAL INOCULATION TEST ON MICE

The aim of this study was to produce Listeria monocytogenes biofilms suitable for virulence assays and to determine whether the released bacteria had the same virulence potential as their planktonic counterparts. Biofilms of Listeria monocytogenes LO28 strain, with or without Sphingomonas paucimobilis CCL10 strain, containing up to 7 log₁₀ cfu/cm² were produced in polypropylene syringes. The virulence of strain LO28 was analyzed in mice after intravenous, subcutaneous and oral inoculation. Its virulence level in binary cultures was not significantly different from that of monocultures. L. monocytogenes LO28 virulence in biofilms was lower than that of their planktonic counterparts after oral inoculation. Our results suggest that biofilms pose no greater health risk to the consumer than planktonic bacteria.     

High Velocity Oxyfuel Deposition for Low Surface Roughness PS304 Self-Lubricating Composite Coatings

Efforts were made to achieve lower (R _q < 0.1 μm) initial RMS roughnesses of PS304 coatings so that they may be considered for foil bearings operating under increasingly severe conditions that result in smaller air film thicknesses. Attainable roughness of conventional plasma-sprayed PS304 coatings has been typically R _q > 0.25 μm, as limited by porosity in the deposited coating and surface irregularities correspondingly formed upon finishing. Initial attempts at achieving dense coatings by instead using a high-velocity oxyfuel (HVOF) flame-spraying process failed due to insufficient heating and softening of the NiCr and Cr ₂ O ₃ constituents of the PS304 feed powder, which rebounded from the steel target substrate and resulted in low deposition yield. Efficient HVOF deposition by a hydrogen-fueled system was achieved using NiCr and Cr ₂ O ₃ constituent particles of reduced size that were more effectively heated. The resultant dense coatings provided roughnesses as low as R _q = 0.05 μm upon polishing. Tribological performance of these HVOF coatings was evaluated against Inconel X-750 in thrust-washer tests at a sliding speed of 5.4 m/s, with contact pressures of 20 and 40 kPa, and ambient or 500°C temperatures. The wear and friction performances in direct sliding contact, as would exist upon loss of separating air-bearing film, of the PS304 coatings produced by HVOF are found to be similar to those deposited by the plasma spray process.     

AN OPTICAL METHOD TO STUDY THE KINETICS OF CLEANING MILK DEPOSITS BY SODIUM HYDROXIDE

An optical sensor was devised to observe cleaning kinetics of heat exchange surfaces fouled by milk and to study the influence of some parameters on them. The sensor works by sensing the attenuation of incident light by the suspension of deposits which are removed by the cleaning solution. The cleaning is carried out without recycling the cleaning solution. The on-line collected numerical data are converted into concentration values by the use of an empirical correlation based on samples of freeze dried deposits diluted with soda solutions. The cleaning kinetics and the weight of removed fouled material are computed for each experiment by integrating the concentration versus time curve. Over 20 experiments, carried out on a plate milk pasteurizer have established the validity of the method. The kinetics are interpreted as initially zero order, but first order at the end of the process.     

ASSESSING AGREEMENT BETWEEN HUMAN AND MACHINE CLUSTERINGS OF IMAGE DATABASES

There is currently much interest in the organization and content-based querying image databases. The usual hypothesis is that image similarity can be characterized by low-level features, without further abstraction. This assumes that agreement between machine and human measures of similarity is sufficient for the database to be useful. To assess this assumption, we develop measures of the agreement between partitionings of an image set, showing that chance agreements must be considered. These measures are used to assess the agreement between human subjects and several machine clustering techniques on an image set. The results can be used to select and refine distance measures for querying and organizing image databases.     

Impedance spectroscopy study of anodic growth of thick zirconium oxide films in H2SO4, Na2SO4 and NaOH solutions

Anodic zirconium oxide films were grown potentiodynamically at a constant sweep rate up to the breakdown potential on rod electrodes made of 99.8% metallic zirconium. Different media of different pH were tested, namely 0.5 M H₂SO₄ (pH 0.3), 0.1 M Na₂SO₄ (pH 9) and 0.1 M NaOH (pH 13). By electrochemical impedance spectroscopy and scanning electron microscopy the oxide film thickness was monitored during the voltage scan. The behaviour was found to be different in the presence and absence of sulphate anions. In the presence of SO₄²⁻, the films were dense but breakdown occurred at 300–340 nm. In NaOH, two relaxations appeared above 50 V and were ascribed to a bi-layered coating structure and the maximum layer thickness was 720 nm before breakdown.     

晶粒取向对镍基超合金Inconel 690离子渗氮速率的影响

对镍基超合金Inconel 690进行了离子渗氮处理.利用扫描电镜(SEM)、X射线衍射(XRD)及电子背散射衍射(EBSD)等手段对渗氮层进行了表征.结果表明Inconel 690经低温离子渗氮处理生成氮在奥氏体中的过饱和固溶相(γN相);取向不同的晶粒γN层厚度不同;γN层生长速度在θ<100>(<100>晶向和渗层生长方向的最小夹角)值较小的晶粒内比在θ<100>值较大的晶粒内快,并且γN层厚度与θ<100>大致呈线性关系.     

Physicochemical characterisation of calcium phosphates prepared from milk ultrafiltrates: Effect of the mineral composition

This study deals with the precipitation of calcium phosphate in permeates removed from milks at different pH (6.7, 5.2 and 4.6). An overall high yield of precipitation of calcium and phosphate (70–80%, respectively) was obtained for all precipitates with Ca/P molar ratios close to 1.5. The suspended milk‐derived calcium phosphate (MDCP) precipitates had 8–14 μm size and ?14 to ?28 mV zeta potential. The dried MDCP precipitates were identified as amorphous calcium phosphate (ACP), stable over 18 months of storage at room temperature.     

Towards a simple indicator of water stress in grapevine (Vitis vinifera L.) based on the differential sensitivities of vegetative growth components

Responses of grapevine vegetative growth components to mild, medium and severe soil water deficits were used to identify simple and sensitive indicators for early diagnosis of water stress. Soil water deficit was characterised as the fraction of transpirable soil water (FTSW) remaining in a water‐depleted rootzone. Growth components included the number of emerged leaves on first (Ist) and second (IInd) order lateral branches, the leaf area and internode length of each phytomer of Ist order lateral branches, and the frequency of IInd order lateral branching. These components were measured in a greenhouse on Shiraz (syn. Syrah) grapevines, over a 38‐day period of stabilised soil water regimes. Leaf emergence rate, final leaf area and final internode length of lateral branches I were relatively insensitive to mild and medium water deficits. They only decreased in response to severe water deficits. The frequency of IInd order lateral branching showed a similar trend, but was inhibited at severe water deficits. The leaf emergence rate of lateral branches II was highly sensitive to FTSW, and decreased even in response to mild water deficits. Because measurement of leaf emergence rate is a time consuming process, further analysis of the data was undertaken to identify a simpler but similarly effective indicator of cumulative water deficit. Accordingly, we established that the final length of lateral branches I was sensitive to medium water deficits, while the final ratio of the number of leaves on lateral branches II to the number of leaves on lateral branches I, was sensitive to even mild water deficits. Both of these composite indicators (derived variables) were relatively easy to measure and showed potential as early indicators of water deficits. They were more sensitive to FTSW than was predawn leaf water potential. Moreover, the final ratio of the number of leaves on lateral branches II to the number of leaves on lateral branches I was even more sensitive to FTSW than was stomatal conductance.     

Hybridization and Specialization of Real-time Recurrent Learning-based Neural Networks

In this article, three different methods for hybridization and specialization of real-time recurrent learning (RTRL)-based neural networks (NNs) are presented. The first approach consists of combining recurrent networks with feedforward networks. The second approach continues with the combination of multiple recurrent NNs. The last approach introduces the combination of connectionist systems with instructionist artificial intelligence techniques. Two examples are added to demonstrate properties and advantages of these techniques. The first example is a process diagnosis task where a hybrid NN is connected to a knowledge-based system. The second example is a NN consisting of different recurrent modules that is used to handle missing sensor data in a process modelling task.