Earthworm coelomocytes as nanoscavenger of ZnO NPs

Earthworms can ‘biotransform’ or ‘biodegrade’ chemical contaminants, rendering them harmless in their bodies, and can bioaccumulate them in their tissues. They ‘absorb’ the dissolved chemicals through their moist ‘body wall’ due to the interstitial water and also ingest by ‘mouth’ while soil passes through the gut. Since the advent of the nanotechnology era, the environmental sink has been continuously receiving engineered nanomaterials as well as their derivatives. Our current understanding of the potential impact of nanomaterials and their natural scavenger is limited. In the present investigation, we studied the cellular uptake of ZnO nanoparticles (NPs) by coelomocytes especially by chloragocytes of Eisenia fetida and their role as nanoscavenger. Results from exposure to 100- and 50-nm ZnO NPs indicate that coelomocytes of the earthworm E. fetida show no significant DNA damage at a dose lower than 3 mg/l and have the potential ability to uptake ZnO NPs from the soil ecosystem and transform them into microparticles.     

Ageing-induced solubility loss in milk protein concentrate powder: effect of protein conformational modifications and interactions with water

BACKGROUND: Protein conformational modifications and water‐protein interactions are two major factors believed to induce instability of protein and eventually affect the solubility of milk protein concentrate (MPC) powder. To test these hypotheses, MPC was stored at different water activities (a_w 0.0–0.85) and temperatures (25 and 45 °C) for up to 12 weeks. Samples were examined periodically to determine solubility, change in protein conformation by Fourier transform infrared (FTIR) spectroscopy and water status (interaction of water with the protein molecule/surface) by measuring the transverse relaxation time (T₂) with proton nuclear magnetic resonance (¹H NMR). RESULTS: The solubility of MPC decreased significantly with ageing and this process was enhanced by increasing water activity (a_w) and temperature. Minor changes in protein secondary structure were observed with FTIR which indicated some degree of unfolding of protein molecules. The NMR T₂ results indicated the presence of three distinct populations of water molecules and the proton signal intensity and T₂ values of proton fractions varied with storage condition (humidity) and ageing. CONCLUSION: Results suggest that protein/protein interactions may be initiated by unfolding of protein molecules that eventually affects solubility. Copyright © 2011 Society of Chemical Industry     

A Local Contrast Fusion Based 3D Otsu Algorithm for Multilevel Image Segmentation

To overcome the shortcomings of 1D and 2D Otsu’s thresholding techniques, the 3D Otsu method has been developed. Among all Otsu’s methods, 3D Otsu technique provides the best threshold values for the multi-level thresholding processes. In this paper, to improve the quality of segmented images, a simple and effective multilevel thresholding method is introduced. The proposed approach focuses on preserving edge detail by computing the 3D Otsu along the fusion phenomena. The advantages of the presented scheme include higher quality outcomes, better preservation of tiny details and boundaries and reduced execution time with rising threshold levels. The fusion approach depends upon the differences between pixel intensity values within a small local space of an image; it aims to improve localized information after the thresholding process. The fusion of images based on local contrast can improve image segmentation performance by minimizing the loss of local contrast, loss of details and gray-level distributions. Results show that the proposed method yields more promising segmentation results when compared to conventional 1D Otsu, 2D Otsu and 3D Otsu methods, as evident from the objective and subjective evaluations.      

The effects of phosphorylation of cardiac troponin-I on its interactions with actin and cardiac troponin-C

It is known that the phosphorylation of two serine residues on the NH2-terminal extension specific to cardiac troponin-I (Tn-I) modulates the calcium-dependent activation of the myofilaments. The process by which this occurs remains an unsolved puzzle. We have applied a dissective approach to study the effect of this phosphorylation on the interactions between Tn-I and its partner proteins, actin and troponin-C (Tn-C). Using N-[14C]ethylmaleimide-labelled Tn-I in sedimentation assays with F-actin, we found that the dephosphorylated Tn-I binds to F-actin with pronounced positive cooperativity, both in the absence and the presence of tropomyosin. Phosphorylation of the protein slightly weakens the interaction in the absence of tropomyosin, but the cooperativity remained. In the presence of tropomyosin, phosphorylation of the Tn-I also appeared to slightly weaken the interaction as well but, more significantly, the cooperativity was eliminated. These data can only be explained simply by a cooperative interaction between the monomer units in the actin filament. The interactions between cardiac Tn-I and Tn-C were studied by labelling the Tn-C with the fluorescent probe dansyl aziridine. As expected, the binding of the dephosphorylated Tn-I to Tn-C was strengthened by over 20-fold upon the addition of calcium to the assay. Phosphorylation of the protein, however, had a dramatic effect on the interaction in that it appeared to desensitise the complex to the effect of calcium: the Ka values obtained for both interactions (+/- Ca2+) were almost identical. These results clearly indicate that the phosphorylation of Tn-I in the cardiac system has dramatic effects on the isolated inter-protein interactions. We also discuss the possible significance of such an effect on the interactions of the isolated proteins in their roles within the intact cardiac regulatory complex.     

Application of fracture mechanics in the design and operation of PWRs in France

Fracture mechanics techniques are used to evaluate the risks associated with material aging, the occurrence of fabrication defects or stress corrosion cracks, and to determine the margins with respect to fast fracture resulting from the design and manufacturing practices. Important programs are underway to improve the accuracy and domain of validity of the fracture mechanics methods.     

Retention and Distribution of 1-Naphthol and Naphthol Polymerization Products on Surface Soils

Sorption and extractability of naphthol and naphthol polymerization products (NPP) were evaluated in two surface soils. NPP were generated by the addition of horseradish peroxidase and H2O2 to naphthol solutions in contact with the surface soils. While NPP retention on the forest soil was lower compared to the parent naphthol, no difference in sorption of naphthol and NPP was observed in the agricultural soil. The agricultural soil retained more naphthol and NPP than the forest soil. The NPP sorption behavior noted in this study was in contrast to that of phenol polymerization products observed by other researchers. The presence of phenol and 2,4-dichlorophenol as cosolutes had no significant impact on naphthol or NPP retention on the two soils, and naphthol was more easily extracted from both soils whenever phenol was present as a cosolute. Characterization of the naphthol polymerization products using reverse-phase high-pressure liquid chromatography and octanol-water partitioning indicated that significant fractions of the water-soluble and insoluble NPP were comprised of oligomers that were more polar than the parent 1-naphthol. This decrease in polarity upon polymerization is believed to have been responsible for the NPP retention and binding behavior observed in this study.     

Selection of optimal set of weights in a layered network using genetic algorithms

Genetic algorithms represent a class of highly parallel robust adaptive search processes for solving a wide range of optimization and machine learning problems. The present work is an attempt to demonstrate their effectiveness to search a global optimal solution to select a decision boundary for a pattern recognition problem using a multilayer perceptron. The proposed method incorporates a new concept of nonlinear selection for creating mating pools and a weighted error as a fitness function. Since there is no need for the backpropagation technique, the algorithm is computationally efficient and avoids all the drawbacks of the backpropagation algorithm. Moreover, it does not depend on the sequence of the training data. The performance of the method along with the convergence has been experimentally demonstrated for both linearly separable and nonseparable pattern classes.