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Background: The tertiary system of nucleotide chain (NC) - gold nanoparticles (NPs) - carbon nanotube (CNT) represents a great interest in the modern research and application of the bio-nano-technologies. The application aspects include, for example, the development of electronic mobile diagnostic facilities, nanorobotic design for a drug delivery inside living cell, and so on. The small NC chain represents an important stage in the understanding of the interaction mechanism of a full DNA or RNA molecule with NP and CNT. In this regard, one has to mention the development of the DNA-CNT devices for the purposes of diagnostic applications in the chemical or drug delivery. Methods: For the NC-NP-CNT system, we have built up a series of the molecular dynamics (MD) models with different NC-NP configurations and performed their MD analysis. The entire system (the NC chain, gold NPs and CNT) was allowed to interact with each other by the only VdW forces. The Lennard-Jones short-ranged interaction was assumed between the NC, NP and CNT. For the CNT a many body Tersoff potential having a quantum-chemistry nature was used. So far, the so-called hybrid MD approach was realized, where the quantum-chemistry potential in combination with a classical trajectory calculation applied . Results: The peculiarities of the NC-NP interaction and bond formation inside of a CNT matrix were investigated along with the structural and dynamical behavior. The correlation effects between the weak Van der Waals (VdW) forces and intramolecular vibrations were enlighten for the molecular system consisting of a small nucleotide chain (NC), gold nanoparticles (NPs) and carbon nanotube (CNT) using molecular dynamics (MD) simulation method. Conclusion: The NC intermolecular motions were estimated from MD data thereby building the distance distributions, the angular and dihedral (torsional) bond energy graphs versus simulation time at different temperatures from T=100 K up to 300 K. The MD simulation results have shown that depending on the relative NC-NP position a different scenario of bonding between the NC-NP, within CNT matrix, is possible. We have observed the possibilities of formation of weak, strong and intermediate bonds between the NP-NC, which are overestimated by a presence of CNT matrix as confined environment. The NC chain can form with a particular gold atom a close contact, while with another under the same positional and temperature conditions the weak resultant bonding formation might be possible. We estimated the fluctuations in the NP-NC bonding processes for a single gold atomic case (models 1-3, NC-1NP-CNT), for the two (model 4-6, NC-2NP-CNT) and three (model 7, NC-3NP-CNT) gold particle ones. Thus, a concurrent effect between the NC intramolecular vibrations and a weak VdW interaction between the NC and gold NP were studied in detail.

Globalization of the trade in agricultural commodities has contributed signii¬cantly to the discussion about potential hazards involved and has increased in particular the awareness of mycotoxins. Safety awareness in food and feed production has also risen due to the simple fact that methods for testing residues and undesirable substances have become noticeably more sophisticated and more available at all points of the supply chain. Mycotoxins comprise of a family of fungal toxins, many of which have been implicated as chemical progenitors of toxicity in man and animals. There are four classes of mycotoxins of major concern namely aflatoxins, zearalenone, ochratoxins, and fumonisins. Formation of mycotoxins varied betweenspecies as well as within a given species. A variety of physical, chemical, and biological methods to counteract the mycotoxin problem have been reported, but large-scale, practical, and cost-effective methods for detoxifying mycotoxin-containing feedstuffs are currently not available. Detoxii¬cation strategies for the contaminated foods and feeds should be done to reduce or eliminate the adverse actions of mycotoxin to improve food safety and prevent economic losses. The most recent approach to the problem has been the addition to the animal's diet of nonnutritive sorbents that sequester mycotoxins, reduce their gastrointestinal absorption and avoiding their toxic effects on livestock and toxin carryover into animal products. This review comments on the potential hazards of several mycotoxins together with prevention strategy for fungal and mycotoxin contamination. Key words: Mycotoxins, detoxification, aflatoxins, zearalenone, ochratoxins, prevention.

Fish, pathogen and environment are three counterparts who are sharing the same circle of life. To keep fish up to their optimal health, environment should be competently improved and pathogen count/virulence should be seized. Using of bioactive immunostimulants to achieve these objectives is the hypothesis under assessment. Thus, the present study was performed to evaluate the use of shrimp shells derived chitosan as an immunostimulant as well as preventive regime against Aeromonas hydrophila infection of Nile tilapia and to assess its antibacterial/aquatic bio-remediating effects. Results achieved by feeding 1% chitosan as preventive/therapeutic regimes have revealed a remarkably enhanced several innate immunological parameters (e.g., Phagocytic activity/index, NBT, Lysozyme activity and ACH50), increased resistance against A. hydrophila and strikingly improved water quality compared to the 0.5 and 2% chitosan containing diets. Conclusively, experimental results suggest the commercial usage of chitosan as an efficient immunostimulant and bio-remediating agent in aquaculture.

The effect of urea additions on the microbiological and chemical properties of silage, produced from young maize plants (Darawa stage), was studied. Urea treatments, i.e., 0.25%, 0.50%, 0.75%, and 1.00%, stimulated higher densities of the desired microorganisms than the control, while undesired organisms showed lower counts (proteolytic and saccharolytic anaerobes). Addition of 0.25 to 0.50% or urea resulted in the production of high quality silage with pleasant small and high nutritive value, as confirmed by the various microbiological and chemical analyses conducted. Higher levels (0.75 and 1.00%) of urea decreased the quality of the product.

The effect of the herbicide atrazine on Fusarium oxysporum f. fabae and Rhizoctonia solani, the causative agents of wilt and rot, respectively, as well as rhizosphere microflora of broad bean plants was studied. The herbicide was applied at intervals of 30, 20, 10, and 0 days before sowing. Atrazine application reduced both densities and per cent of infection of these two pathogenic fungi, R. solani, however, was sensitive to atrazine itself, while F. oxysporum was affected by atrazine by-products. Rhizosphere flora, i.e., total microbial flora, actinomycetes, phosphate-dissolving bacteria, and fungal flora, were not affected by atrazine, but were deleteriously reduced by its by-products at early stages of plant growth. However, rhizosphere flora attained the normal levels after atrazine by-products had completely disappeared from soil (1 month after application), except for actinomycetes. Therefore, it is recommended to apply atrazine within 20 days before sowing for weed control as well as for controlling wilt and root rot infestations.

Summary The effect of the fungicide Dithan A-40 and the insecticide Cyolane on rhizosphere and soil microflora of broad bean plants cultivated in artificially infested soil with Fusarium oxysporum f. fabae was studied. F. oxysporum inoculation depressed the total microbial flora, actinomycetes and phosphate dissolvers while stimulated total fungi and Fusarium spp. in rhizosphere and soil. Application of Dithan A-40 or Cyolane, in general, stimulated different microbial groups except for total fungi and Fusarium spp. However, stimulation was more obvious in Cyolane treatment. Fungal spectra, in turn, showed a considerable sxift in pesticides treatments. Moreover, wilt incidence was significantly reduced in post-emergence infections, especially in Dithan A-40 treatment.

140 soil samples from the Assiut governorate were examined for pathogenic fungi and actinomycetes. The paraffin-bait technique and a modified sodium citrate-utilizing procedure were used for recovery of Nocardia strains. Five isolations of N. brasiliensis were made by the sodium citrate method while 3 isolates were obtained by the other method. N. gypsoides was isolated for the first time, only the the modified method. It appears that the latter method suppresses to a great extent the growth of saprophytic fungi, hence increasing the possibility of the isolation of Nocardia spp. The effect of keratin enrichment on the isolation of dermatophytes from soil by the hair-bait technique was also investigated. Pretreatment of samples with dog hair or feathers increased the yield of isolates of Microsporum gypseum, Trichophyton terrestre and to a lesser extent, T. mentagrophytes, M. canis was recovered from soil only after its enrichment with dog hair. It is suggested that enrichment with other forms of keratinous material, either separately or in combination, might increase the recovery of keratinophilic fungi from soil.

Summary The effect of different concentrations of Dithan A-40 fungicide on the metabolic activities of the wilt fungus Fusarium oxysporum f. fabae and the root rot agent Rhizoctonia solani was studied. All toxicant concentrations reduced energy generation, total phosphorus and nitrogen content of both fungi. In addition, the toxicant caused a shift in free amino acids pool. As a result of these changes, the mycelium dry weight of both fungi was greatly reduced. R. solani was more sensitive to the toxic effect of Dithan A-40 than F. oxysporum .