Preservation of cold‐stored guavas influenced by package materials

The objective of this study was to evaluate the influence of package materials on the preservation of cold‐stored ‘Kumagai’ guavas. The treatments were: PO2, co‐extruded polyolephinic film with gas injection (5% O₂/5% CO₂/N₂); PO3, co‐extruded polyolephinic film with gas injection (5% O₂/5% CO₂/N₂); LDPE, linear low density polyethylene film; LDPE‐gas, linear low density polyethylene film with gas injection (3% O₂/8% CO₂/N₂); PVC, polyvinylchloride stretch film; PO1, co‐extruded polyolephinic film and control: non‐packaged guavas. Guavas were stored at 10 ± 1°C/80–90% RH for 21 days, and then transferred to room temperature. Gas composition within the package headspace was analysed during storage and the physical and chemical characteristics of the guavas were evaluated daily during ripening. The modified atmosphere provided by PO1 film was insufficient to promote the benefit of senescence control. Although PVC provided an atmosphere close to that recommended, it did not preserve the colour and pulp firmness. PO2, PO3, LDPE and LDPE‐gas retarded the senescence process of the guavas during 21 days at 10°C plus 2 days at room temperature, but harmed the normal ripening of guavas in some aspects. This can be explained by reduced O₂ and elevated CO₂ levels within these four packages. None of the packages influenced the titratable acidity and the soluble solids, but they did harm ascorbic acid synthesis. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of voltage harmonics on the operation of solid-state relaysin industrial applications

The results of a study on the effects of voltage and current harmonics on the operation of four types of solid-state relays (SSRs) used in control schemes of many industrial applications are presented. This study started after repeated malfunctions of electrophotographic printers in some data processing centers. The misoperation of zero-switching SSRs was suspected as the cause of the malfunction. Tests on the SSRs were performed using a single-phase harmonic generator and a LeCroy digital oscilloscope with signal processing software capabilities. The results reported indicate that voltage harmonic distortion may cause a delay in the turn-on time of more than a cycle. In some cases, complete failure to turn on or off may occur. Recommendations based on academic research, user's experience, and manufacturers viewpoints are given     

Use of amphotropic retroviral vectors for gene transfer in human colon carcinoma cells

Previous studies in rodent models have demonstrated the feasibility of gene transfer to the stem cells of the intestinal epithelium using ecotropic retroviral vectors delivered luminally. This report represents a next step toward targeting the human intestine as a site for somatic gene therapy. The first experiment assessed the viability of amphotropic retroviral vectors in the luminal environment. It was found that after 4 hr at 37 degrees C in luminal effluent, the loss of titer was no greater than when incubated in control media. Likewise, neither the vector nor the target cells were adversely affected by N-acetylcysteine, which is likely to be used as a preparatory agent for mucus removal. To determine whether human intestinal cells are transducible by these vectors, three colon carcinoma cell lines were studied: HT-29, T84, and Caco-2. All were transduced; however, the expression of the reporter gene was highest in the HT-29 cells. Subsequent studies using these cells showed that with regular stocks of vector, gene transfer peaked at a stock dilution of 1/10 and declined at full strength. This problem could be partially overcome by centrifugal concentration of the retroviral stocks. With this approach, gene transfer increased with increasing particles up to 10x regular stock titers but was inefficient at 100x. Overall, these findings provide encouraging evidence that amphotropic retroviral vectors may eventually be used for in vivo gene transfer into human intestinal epithelium. However, they also point to the need for improved methods of concentrating retroviral vectors.     

Effects of low level microwave radiation on the digestive transit of the rat.

The effects of low level microwave radiation (3-4 mW/cm2--2450 MHz) during 4 and 8 h on the WISTAR Rat digestive transit has been studied. The results showed no effect after 4 h radiation and an acceleration of the digestive transit after 8 h of radiation (p less than .001). The acceleration of the digestive transit was still observed after 24 h (p less than .001). 60-90 s after radiation time the rectal temperature of radiated animals did not differ from the controls.     

Carnauba Wax and Modified Atmosphere in Refrigerated Preservation of ‘Tahiti’ Acid Limes

Peel yellowing and loss of fruit mass reduce the useful life of acid limes and limit their commercialization. The goal of the present study was to prolong the post‐harvest preservation of acid limes using wax and packaging. Fruits were harvested, selected, disinfected, treated with fungicide, coated with Carnauba wax and placed in cardboard boxes wrapped with different plastic packaging. A fruit lot treated only with wax coating was used as a control. The fruits were stored at 10°C for 24 days followed by 6 days at 20°C. The gas atmosphere inside the packages was analysed during storage. The loss of mass, color index, titratable acidity, and total chlorophyll, ascorbic acid, soluble solids, acetaldehyde and ethanol concentrations of the fruits were measured. The combined use of wax coating and plastic Cryovac^® D‐955 (Cryovac Brasil Ltda, São Paulo, Brazil) and Vegetal Pack^® (Eletropolimeros do Brasil Ltda, São Paulo, Brazil) films resulted in better post‐harvest preservation of acid limes compared with only wax coating because the combined treatment maintained the green peel color following 30 days of storage in addition to resulting in lower loss of mass and maintaining chemical characteristics adequate for commercialization. The LDPE (low density polyethylene) and Xtend^® packaging (Stepac Brasil Ltda, São Paulo, Brazil), although they prevented peel degreening, did not result in an adequate atmosphere to maintain the quality of limes due to the accumulation of high concentrations of acetaldehyde and ethanol, especially for the LDPE packaging. LDPE drastically changed the atmosphere surrounding the fruit, resulting in loss of the characteristic pulp color, in addition to conferring an alcohol odor. Copyright © 2015 John Wiley & Sons, Ltd.     

Logic control law design for automated manufacturing systems

To respond rapidly to the highly volatile market, the reconfigurable manufacturing systems (RMS) have brought forward challenging issues. First of all there is a need to build a formal model of a manufacturing configuration. Second it has to be rather easy to derive the models associated to the manufacturing configuration changes (reconfiguration) from such an initial model. An off-line method of rapid design of an optimal logic control law (configuration) based on Petri net (PN) is presented in this paper. From a controlled system modeling point of view, the main characteristics of the level 1 of the CIM architecture are depicted. Subsequently, the formal tool used in the automated planning field is extended to provide a controlled system model. The concept of operation is structured in order to introduce the behavioral properties of the operations. A four-step method is then proposed to design a logic control law that satisfies several goals: reduction of the lead time, satisfaction of the work orders objectives, minimization of the time cycle. Finally, the proposed design method is illustrated on a manufacturing cell.     

Evaluation of plastic packages for guava refrigerated preservation

Guavas cv. ‘Kumagai’ were packed in several plastic materials and stored at 10°C and 85–90% relative humidity (RH) for 7, 14, 21 and 28 days (+3 days at 25°C). The plastic materials studied were: multilayer co‐extruded polyolephine film with selective permeability (PSP), low‐density polyethylene film (LDPE), LDPE film with mineral incorporation (LDPEm) and heat‐shrinkable polyolephine film (SHR). Guavas not packed were taken as control samples. The physicochemical characteristics of the fruits, O₂ and CO₂ transmission rates of the packaging materials and gas composition at the package headspace were evaluated. The LDPE film, 69 µm in thickness, with the lowest permeability to both O₂ and CO₂, led to anaerobiosis and high CO₂ concentration inside the packages and promoted physiological disturbances and changes in fruit flavour. The SHR film, 15 µm in thickness, was the most permeable to CO₂ and had quite high O₂ transmission, which modified the inner atmosphere of the packages slightly. The fruits packed in this film showed a poorer quality than the controls, possibly due to the heat produced during the shrinking of the film. The LDPEm film, 24 µm in thickness, was almost as permeable to CO₂ but had reduced O₂ transmission, promoting an atmosphere of equilibrium of 3% O₂ and 4.5% CO₂. Fruits packed in this film kept their skin colour and pulp firmness, suitable for consumption up to 14 days. The PSP film, 35 µm in thickness, had the greatest O₂ transmission but just over half of the CO₂ transmission of LDPEm, promoting an atmosphere of equilibrium of 0.5% O₂ and 4.5% CO₂ inside the packages. Fruits packed in such packages kept their physicochemical characteristics up to 21 days. Copyright © 2001 John Wiley & Sons, Ltd.     

Maximizing the configuration robustness for parallel multi-purpose machines under setup cost constraints

This paper focuses on the configuration of a parallel multi-purpose machines workshop. An admissible configuration must be chosen in order to ensure that a load-balanced production plan meeting the demand exists. Moreover, the demand is strongly subject to uncertainties. That is the reason why the configuration must exhibit robustness properties: the load-balancing performance must be guaranteed with regard to a given range of uncertainties. A branch-and-bound approach has been developed and implemented to determine a cost-constrained configuration that maximizes a robustness level. Computational results are reported for both academic and industrial-scale instances. More than 80% of the academic instances are solved to optimality by the proposed method. Moreover, this method appears to be a good heuristic for industrial-scale instances.