Fate of foodborne bacterial pathogens in pesticide products

The effects of diluting concentrated pesticide products with water containing Escherichia coli O157:H7 (human, bovine and ground meat strains), Salmonella typhimurium, Salmonella enteritidis, Shigella sonnei, Shigella flexneri and Listeria monocytogenes were investigated. Individual cultures were inoculated at about 10² colony‐forming units (cfu) ml^?1 into the following commercial pesticide products—Roundup, Poast & Merge, Gramoxone, Afolan, 2,4‐D amine, Dithane M45, Benlate, Bravo 500, Ridomil 240EC, Thiram 75WP, Sevin XLR+, Lorsban 4E, Diazinon 500, Ambush 500EC and Lagon 480E—following dilution with sterile tap water to recommended spray application concentrations (pesticide solution). Following incubation at 22 °C for 1 h, survivor levels for all three E coli O157:H7 strains in pesticide solutions of Roundup, Poast & Merge, Gramoxone, Dithane M45, Ridomil 240EC and Lagon 480E were lower (P ≤ 0.05) compared to their survival in water. In several pesticide solutions (Afolan, Bravo 500, Lorsban 4E and Ambush 500EC), survivor levels were no different (P≥0.05) from the control after 1 h; however, by 24 h, population levels of all strains in these four pesticide solutions were higher (P ≤ 0.05) than those observed at 1 h. Overall, similar survivor or growth patterns were observed with the remaining bacteria, with the exception of S flexneri. For this bacterium, survival or growth was poor, especially in Bravo 500, which consistently supported substantial growth of the other micro‐organisms. Time course growth studies over 96 h at 22 °C were conducted with Salmonella, Shigella, Listeria and E coli O157:H7 in solutions of Afolan, Bravo 500, Lorsban 4E and Ambush 500EC. Overall, a 100 to 1060‐fold increase in population was usually obtained in these pesticide solutions by 96 h. Changes in either the initial inoculum level of E coli O157:H7 from about 10² to 10⁴ cfu ml^?1 or temperature (from 20–22 to 31 °C) and concentration (from 0.5 to 1.5 times the recommended spray concentration) were shown to affect its growth in the pesticide solutions. The findings of this study indicate that some pesticide products, when diluted using contaminated water, may have the potential to promote growth of pathogens which could increase the risk of more widespread contamination of standing crops, including fruits. © 2001 Society of Chemical Industry     

Special purpose processor for parameter identification of CNC second order servo systems on a low-cost FPGA platform

The parameter identification process has an important role in servo systems tuning on computer numerical control (CNC) machine tools. The parameter identification is mostly done off-line due to the high computational load carried by the identification algorithms. In this work, we present a novel hardware architecture for an application specific processor implementing the recursive least-squares algorithm for the on-line identification. The developed processor is simulated and tested with the necessary elements to perform the CNC machine servo system control. The system was implemented in a low-cost FPGA, getting a maximum sample frequency of 40 kSps.     

In vitro microbial metabolism of fumonisin B1

There is a lack of information on the effect of swine caecal microbiota on fumonisin metabolism. In this in vitro study, the biotransformation of fumonisin B₁ (FB₁) by the gut microbiota of adult, healthy pigs was examined. Suspensions of caecal contents and McDougall buffer solution were incubated anaerobically with pure FB₁ for 0, 12, 24, 48 and 72 h. After 48 h, the conversion of FB₁ to partially hydrolysed FB₁ (46%) was nearly equal to the percentage ratio of FB₁, while by 72 h it was 49%. In vitro, the conversion of fumonisin B₁ to aminopentol was less than 1%. The results show that the caecal microbiota are capable of transforming fumonisin B₁ to the above metabolites. Further studies on FB₁ metabolism in the small intestine are clearly justified.     

光电能及其效益

南非目前正开展一项崭新而雄心勃勃的计划－改善偏远农村地区的能源供应状况。该计划的一个重要组成就是授予７家私营协营体特许权，分别在不同地区安装３５万台家用太阳能光电系统。该项计划对于农村地区能源发展具有突破性的意义。     

Corrective maintenance through dynamic work allocation and pre-emption: case study and application

This case study develops an innovative management and scheduling system for corrective maintenance of machines in a manufacturing facility. The study also involves a comparative evaluation of the proposed and the existing systems under a spectrum of operating conditions. A comprehensive simulation is used to evaluate system performances under a variety of settings which include reliability, service level, and cost consequences. The analysis is based on a full factorial experimental design. In summary, the developed self-regulating management system which involves dynamic work allocation and pre-emption is shown to yield higher machine availability and higher mechanic utilisation even with fewer mechanics. The study also finds that the new system is more streamlined, agile, and robust although it is subject to more-constrained machine reliability and mechanic service time environments. Further, a major reduction of current manpower can still achieve at least 95% machine availability, illustrating the cost effectiveness and efficacy of the developed system. This rule-based corrective maintenance system can be operated in uncertain environments on a real-time basis without additional reformatting costs and provides a competitive measure to deal with managerial issues such as low retention rate for skilled mechanics, highly uneven training levels and pay scales. The financial consequences and gains in strategic advantage with respect to the facility's operational structure are promising after implementation. Moreover, the system developed in this case study represents a meaningful starting point for a more vigorous theoretical research on the bucket brigade system to different functions in industrial and operations management.     

Modulation of Induced Cytotoxicity of Doxorubicin by Using Apoferritin and Liposomal Cages

Doxorubicin is an effective chemotherapeutic drug, however, its toxicity is a significant limitation in therapy. Encapsulation of doxorubicin inside liposomes or ferritin cages decreases cardiotoxicity while maintaining anticancer potency. We synthesized novel apoferritin- and liposome-encapsulated forms of doxorubicin (“Apodox” and “lip-8-dox”) and compared its toxicity with doxorubicin and Myocet on prostate cell lines. Three different prostatic cell lines PNT1A, 22Rv1, and LNCaP were chosen. The toxicity of the modified doxorubicin forms was compared to conventional doxorubicin using the MTT assay, real-time cell impedance-based cell growth method (RTCA), and flow cytometry. The efficiency of doxorubicin entrapment was 56% in apoferritin cages and 42% in the liposome carrier. The accuracy of the RTCA system was verified by flow-cytometric analysis of cell viability. The doxorubicin half maximal inhibition concentrations (IC₅₀) were determined as 170.5, 234.0, and 169.0 nM for PNT1A, 22Rv1, and LNCaP, respectively by RTCA. Lip8-dox is less toxic on the non-tumor cell line PNT1A compared to doxorubicin, while still maintaining the toxicity to tumorous cell lines similar to doxorubicin or epirubicin (IC₅₀ = 2076.7 nM for PNT1A vs. 935.3 and 729.0 nM for 22Rv1 and LNCaP). Apodox IC₅₀ was determined as follows: 603.1, 1344.2, and 931.2 nM for PNT1A, 22Rv1, and LNCaP.     

Dynamic and geometric error assessment of an XYC axis subset on five-axis high-speed machine tools using programmed end point constraint measurements

This paper presents a technique for assessing the volumetric errors on a five-axis machine tool for motion involving two linear axes and one rotary axis at selected feed rates using data from two sources. The first source of data is obtained through a programmed end point constraint procedure with measurement of the 3D volumetric positioning errors between a point on the tool holder and another fixed to the machine table reference frame. The tests involve maintaining the nominal coincidence of these two points whilst exercising the three axes. The second source of data is the position feedback signal from the encoder provided by the machine controller. Tests were carried out at low and high feed rates to evaluate the effect of geometric and dynamic errors. Polynomial functions are used to represent and then predict the geometric errors. The predicted geometric errors are then added to the dynamic errors provided by the servo errors from position feedback signals and propagated to the tool centre point and are compared with the measured volumetric errors. It shows that the influence of the geometric errors are dominant at low feed, whereas the effects of the servo errors of the linear axes become dominant as the feed increases, reaching 80% of the total error at a feed of 10,000 mm/min.