Effect of anilinopyrimidine resistance on aflatoxin production and fitness parameters in Aspergillus parasiticus Speare

Mutants of Aspergillus parasiticus resistant to the anilinopyrimidine fungicides were isolated at a high mutation frequency after UV-mutagenesis and selection on media containing cyprodinil. In vitro fungitoxicity tests resulted in the identification of two predominant resistant phenotypes that were highly (R₁-phenotype) and moderately (R₂-phenotype) resistant to the anilinopyrimidines cyprodinil, pyrimethanil and mepanipyrim. Cross-resistance studies with fungicides from other chemical groups showed that the highly resistance mutation(s) did not affect the sensitivity of R₁-mutant strains to fungicides affecting other cellular pathways. Contrary to that, a reduction in the sensitivity to the triazoles epoxiconazole and flusilazole, the benzimidazole carbendazim, the phenylpyrrole fludioxonil, the dicarboximide iprodione and to the strobilurin-type fungicide pyraclostrobin was observed in R₂-mutant strains. Study of fitness parameters of anilinopyrimidine-resistant strains of both phenotypic classes showed that all R₁ mutant strains had mycelial growth rate, sporulation and conidial germination similar to or even higher than the wild-type parent strain, while these fitness parameters were negatively affected in R₂ mutant strains. Analysis of the aflatoxin production showed that most R₁ mutant strains produced aflatoxins at concentrations markedly higher than the wild-type parent strain. A considerable reduction in the aflatoxin production was observed on cultured medium and on wheat grains by all R₂ mutant strains, indicating a possible correlation between fitness penalties and aflatoxigenic ability of A. parasiticus. The potential risk of increased aflatoxin contamination of agricultural products and their byproducts by the appearance and predominance of highly aflatoxigenic mutant strains of A. parasiticus resistant to the anilinopyrimidines is discussed.     

A phenomenological analysis of Mode I fracture of adhesively-bonded pultruded GFRP joints

The fracture behavior of adhesively-bonded pultruded joints was experimentally investigated under Mode I loading using double cantilever beam specimens. The pultruded adherends comprised two mat layers on each side with a roving layer in the middle. An epoxy adhesive was used to form the double cantilever beam specimen. The pre-crack was introduced in three different depths in the adherend in order to induce crack initiation and propagation between different layers and thus investigate the effect of these different crack paths on the strain energy release rate. Short-fiber and roving bridging increased the fracture resistance during crack propagation. Specific levels of critical strain energy release rates could be attributed to each of the crack paths, with their levels depending on the amount of short-fiber bridging and the presence of a roving bridge. The different levels of critical strain energy release rate could be correlated to the morphology of the fracture surface and the strain energy release rate can thus be determined visually without any measurement.     

Sensitivity of Penicillium expansum field isolates to tebuconazole, iprodione, fludioxonil and cyprodinil and characterization of fitness parameters and patulin production

A total of 236 Penicillium expansum field isolates from decayed apple fruit collected from packinghouses and processing industries located in the region of Imathia, Northern Greece were tested for their sensitivity to tebuconazole, fludioxonil, iprodione and cyprodinil. Preliminary fungitoxicity tests on the response of the isolates showed several phenotypes, distinguished according to their sensitivity to fungicides tested. The EC₅₀ values ranged from 0.64 to 5 (average = 0.98) μg/ml for iprodione, 0.9 to 7.3 (average = 2.66) μg/ml for tebuconazole, 0.008 to 1.28 (average = 0.55) μg/ml for cyprodinil and from 0.013 to 0.47 (average = 0.08) μg/ml for fludioxonil. A bimodal distribution of the EC₅₀ values of isolates with distinct sensitive and resistant populations to fludioxonil and tebuconazole were observed. In the case of cyprodinil, a much broader, hundred-fold, range of sensitivity was found, probably indicating that some isolates are relatively insensitive to cyprodinil compared to the most sensitive ones. Isolates exhibiting simultaneously reduced sensitivity to tebuconazole and fludioxonil or tebuconazole and iprodione or to tebuconazole and cyprodinil were also observed at low frequencies. A small portion of the population (7.5%) showed multiple resistance to tebuconazole, fludioxonil and iprodione. Study of fitness determining parameters showed that the resistance to tebuconazole, fludioxonil and iprodione had a significant adverse effect on mycelial growth rate and pathogenicity. Contrary to that, these fitness parameters were not affected in the isolates showing reduced sensitivity to cyprodinil. Analysis of patulin production on YES-agar growth medium and on artificially inoculated apple fruit showed that all isolates were mycotoxigenic. Most of the cyprodinil-insensitive isolates produced patulin at concentrations similar to or relatively higher (up to 1.5-fold on growth medium) than the sensitive ones. In contrast, a significant reduction (up to 98% of multiple resistant isolates) in patulin production was observed in all other phenotypes, indicating an adverse effect of fitness penalties on the mycotoxigenic ability of resistant isolates. The above mentioned data clearly show a considerable risk for the selection of P. expansum isolates resistant to fludioxonil, iprodione, tebuconazole and cyprodinil. The potential risk of increased patulin contamination of apples and their byproducts by the appearance and predominance of highly mycotoxigenic isolates of P. expansum resistant to the anilinopyrimidines is discussed.     

Treating any polymer dissolved in water as polymer presenting a draining effect

The statistical segment length of a large number of flexible and rigid polymers dissolved in water is calculated. For these calculations, the constant value of the Flory??s parameter ?? (???=?2.6?×?10²³?cgs) along with its values obtained from an equation proposed for polymers exhibiting a significant draining effect (Colloid Polym Sci 273: 626?C632, 1995) are used. Applying the first approximation for ??, a very low statistical segment length for the polymers dissolved in water is obtained, while in the second case the statistical segment length is almost identical with the values obtained when these polymers are dissolved in an organic solvent. Moreover, we show that there is an optional application of the modified universal calibration of the gel permeation chromatography (J Polym Sci B Polym Phys 41: 707?C710, 2003), only if we use values of ?? obtained via the second approximation for polymers presenting a significant draining effect (Colloid Polym Sci 273: 626?C632, 1995).     

Designing and implementing the transition to a fully digitalhospital

The increase in the number of examinations performed in modern healthcare institutions in conjunction with the range of imaging modalities available today have resulted in a tremendous increase in the number of medical images generated and has made the need for a dedicated system able to acquire, distribute, and store medical image data very attractive. Within the framework of the Hellenic R&D program, we have designed and implemented a picture archiving and communication system for a high-tech cardiosurgery hospital in Greece. The system is able to handle in a digital form images produced from ultrasound, X-ray angiography, γ-camera, chest X-rays, as well as electrocardiogram signals. Based on the adoption of an open architecture highly relying on the DICOM standard, the system enables the smooth transition from the existing procedures to a fully digital operation mode and the integration of all existing medical equipment to the new central archiving system     

Integrating multimedia archives: the architecture and the content layer

In the last few years, numerous multimedia archives have made extensive use of digitized storage and annotation technologies. Still, the development of single points of access, providing common and uniform access to their data, despite the efforts and accomplishments of standardization organizations, has remained an open issue as it involves the integration of various large-scale heterogeneous and heterolingual systems. This paper describes a mediator system that achieves architectural integration through an extended three-tier architecture and content integration through semantic modeling. The described system has successfully integrated five multimedia archives, quite different in nature and content from each other, while also providing easy and scalable inclusion of more archives in the future.     

Diffusion kinetic study of cadmium(II) biosorption by Aeromonas caviae

The removal of cadmium from aqueous solution by sorption on Aeromonas caviae particles was investigated in a well‐stirred batch reactor. Equilibrium and kinetic experiments were performed at various initial bulk concentrations, biomass loads and temperatures. Biosorption equilibrium was established in about 1 h and biosorption was well described by the Langmuir and Freundlich biosorption isotherms. The maximum biosorption capacity was found as 155.32 mg Cd(II) g^?1 at 20 °C. The obtained sorption capacity is appreciably high for most experimental conditions; so A caviae may be considered as a suitable biosorbent for the removal of cadmium. Moreover, the sorption rate of cadmium onto A caviae particles was particularly sensitive to initial bulk concentration and solid load. A detailed analysis was conducted, examining several diffusion (external and intraparticle) kinetic models in order to identify a suitable rate expression. The results are discussed and indicate that biosorption of cadmium is a complex process that is described more correctly by more than one model. Copyright © 2004 Society of Chemical Industry     

Photopolymerization of methyl methacrylate and 2-(dimethylamino) ethyl methacrylate induced by diacetoxyiodobenzene in the presence of radical inhibitors

Summary Polyvalent iodine compounds such as diacetoxyiodobenzene, (CH₃COO)₂IC₆H₅ (DAI), and bis(trifluoroacetoxy) iodobenzene, (CF₃COO)₂IC₆H₅ (BTI), are efficient initiators of cationic and radical polymerizations. To confirm the radical mechanism of DAI-induced polymerization of methyl methacrylate (MMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA), a study has been performed in the presence of the radical inhibitor 2,3,5,6-tetrachloro-p-benzoquinone (TCQ) and its complex with triethylamine (TEA). The polymerization kinetics and the effect of irradiation intensity have been studied.     

Truncated chlorophyll antenna size of the photosystems—a practical method to improve microalgal productivity and hydrogen production in mass culture

Unicellular microalgae hold the promise of commercial exploitation in mass culture for hydrogen and biomass production. In any microalgal production system, the achievable photosynthetic productivity and light utilization efficiency of the algae are the single most important factors in the determination of cost. Microalgal mass cultures growing under full sunlight have a low per chlorophyll (Chl) productivity since, at high photon flux densities, the rate of photon absorption by the Chl antenna far exceeds the rate at which photons can be utilized for photosynthesis. Excess photons are dissipated as fluorescence or heat. Up to 80% of absorbed photons could thus be wasted, reducing light conversion efficiencies and cellular productivity to fairly low levels. This shortcoming could possibly be alleviated by the development of microalgal strains with a limited number of Chl molecules in the light-harvesting antenna of their photosystems, i.e., strains that have a truncated Chl antenna size. It is expected that individually, such microalgae will not be able to saturate rates of photosynthesis and, thus, will not be subject to wasteful dissipation of excitation energy. In turn, the productivity of the mass culture will be improved. The method of choice to reach the objective of a “truncated light-harvesting Chl antenna” size (tla) employed DNA insertional and chemical mutagenesis of the unicellular green algae Chlamydomonas reinhardtii and Dunaliella salina, followed by a rigorous screening protocol to identify mutants with a smaller light-harvesting Chl antenna size. Molecular and genetic analyses of isolated tla strains were performed. Biochemical and physiological analyses in terms of photosynthetic productivity and light conversion efficiencies are presented. The results show that a truncated Chl antenna size of PSII is more important than that of PSI in terms of the photosynthetic productivity of a mass culture. A list of genes that confer a “truncated light-harvesting Chl antenna” size to green algae is being compiled for future application in algal hydrogen and biomass production.     

Polymers in mixed solvents: linear representation of viscosity data as a function of molecular weight

In this paper the corrected Stockmayer-Fixman-Burchard equation recently proposed¹³ is applied to the case of polymers dissolved in mixed solvents. A linear plot for viscosity over a very broad range of molecular weights is observed. The unperturbed dimensions of polymers obtained in mixed solvents are related to the thermodynamic properties of the solvent mixtures.