Showing papers on "Water environment published in 2007"

UV filters : From sunscreens to human body and the environment

Abstract: Recognition of the harmful effects of ultraviolet (UV) radiation on the skin has triggered development of organic chemicals (commonly referred as UV filters) that can absorb UV radiation and attenuate the negative effects of sunlight exposure. Depending on the properties and the intended degree of protection, a wide array of combinations is being marketed as delivering protection against most kinds of UV-induced skin damage. However, some UV filters have dermatological implications, so maximum applicable concentrations have been established. To monitor to what extent commercial products comply with the mandatory limits, several analytical methods have been used for their determination in cosmetics and related products. Further research on the efficacy of UV filters applied on the skin surface has brought to light a gradual attenuation of their UV-protective capacity that cannot solely be attributed to photo-induced decomposition. Investigations carried out to elucidate the reasons underlying this behaviour concluded that UV filters may be systematically absorbed through the skin surface or even released during bathing and washing activities. These observations gave rise to numerous studies aiming to investigate the magnitude and effects of skin penetration as well as accumulation in the water environment. Because of the need for more in-depth investigation into the behavior of UV filters, the initial demand for product certification has been extended to include reliable analytical methods to determine these substances at low concentration levels and in complex matrices (e.g., biological and environmental samples). Until now, most of the available methods, although designed to cover a large variety of substances, quantify them at only high-mg/L levels; however, recently, researchers have paid special attention to developing more sensitive procedures able to determine these substances in biological tissues and fluids or environmental samples at ng/L levels without matrix interferences. This article gives a comprehensive outline of the accumulated knowledge on UV-filter determination in biological and environmental samples and encourages further research in this new, challenging field of analytical, health and environmental science.

New POPs in the water environment: distribution, bioaccumulation and treatment of perfluorinated compounds – a review paper

Abstract: Perfluorinated compounds such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are emerging environmental pollutants. From the available literature, tap and surface water samples in several countries were found to be contaminated with PFOS and PFOA. These compounds were detected globally in the tissues of fish, bird and marine mammals, but their concentrations in animals from relatively more industrialized areas were greater than those from the less populated and remote locations. The bioconcentration factors (BCFs) of PFOS in fish were in the range of 10,000 or above, while the BCF of PFOA in fish was below 200. Blood samples of occupationally exposed people and the general population in various countries were found to contain PFOS and PFOA which suggested a possibility of atmospheric transport of these compounds. There is still a dearth of information about the environmental pathways of PFOS and PFOA. Some advanced oxidation methods, photocatalysis, adsorption, and reverse osmosis membrane filtration were found effective in degrading or removing PFOS and PFOA from the water environment. The presence of these compounds in the tap water, surface water and animal and human tissues indicates their global contamination and bioaccumulative phenomena in the ecosystems.

Proton transport and the water environment in nafion fuel cell membranes and AOT reverse micelles.

Abstract: The properties of confined water and diffusive proton-transfer kinetics in the nanoscopic water channels of Nafion fuel cell membranes at various hydration levels are compared to water in a series of well-characterized AOT reverse micelles with known water nanopool sizes using the photoacid pyranine as a molecular probe. The side chains of Nafion are terminated by sulfonate groups with sodium counterions that are arrayed along the water channels. AOT has sulfonate head groups with sodium counterions that form the interface with the reverse micelle's water nanopool. The extent of excited-state deprotonation is observed by steady-state fluorescence measurements. Proton-transfer kinetics and orientational relaxation are measured by time-dependent fluorescence using time-correlated single photon counting. The time dependence of deprotonation is related to diffusive proton transport away from the photoacid. The fluorescence reflecting the long time scale proton transport has an approximately t-0.8 power law decay in contrast to bulk water, which has a t-3/2 power law. For a given hydration level of Nafion, the excited-state proton transfer and the orientational relaxation are similar to those observed for a related size AOT water nanopool. The effective size of the Nafion water channels at various hydration levels are estimated by the known size of the AOT reverse micelles that display the corresponding proton-transfer kinetics and orientational relaxation.

Organic crystal hydrates : what are the important factors for formation

Abstract: A database study of 34 770 accurate organic crystal structures reveals that the most important factor determining a higher frequency of hydrates is the sum of the average donor and acceptor counts for the functional groups. Different parameter forms for donor/acceptor properties were investigated for correlation with formation of hydrates, and are discussed. We did not find that the donor/acceptor ratio or the molecular weight significantly affects the hydrate formation. We also examined a wide range of calculated molecular properties and found that increasing polar surface is correlated with increasing hydrate formation. The water environment pattern of donor and acceptor hydrogen bonds in the crystal is influenced by the donor/acceptor ratio of the molecule.

Effect of competing solutes on arsenic(V) adsorption using iron and aluminum oxides.

Abstract: The study focused on the effect of several typical competing solutes on removal of arsenic with Fe 2 O 3 and Al 2 O 3 . The test results indicate that chloride, nitrate and sulfate did not have detectable effects, and that selenium(IV) (Se(IV)) and vanadium(V) (V(V)) showed slight effects on the adsorption of As(V) with Fe 2 O 3 . The results also showed that adsorption of As(V) on Al 2 O 3 was not affected by chloride and nitrate anions, but slightly by Se(IV) and V(V) ions. Unlike the adsorption of As(V) with Fe 2 O 3 , that with Fe 2 O 3 was affected by the presence of sulfate in water solutions. Both phosphate and silica have significant adverse effects on the adsorption of As(V) adsorption with Fe 2 O 3 and Al 2 O 3 . Compared to the other tested anions, phosphate anion was found to be the most prominent solute affecting the As(V) adsorption with Fe 2 O 3 and Al 2 O 3 . In general, Fe 2 O 3 has a better performance than Al 2 O 3 in removal of As(V) within a water environment where multi competing solutes are present.

Sensitive biosensor array using surface plasmon resonance on metallic nanoslits

Abstract: Chip-based biosensor arrays for label-free and high-throughput detection were fabricated and tested. The sensor array was composed of a 150-nm-thick, 50-nm-gap, and 600-nm-period gold nanoslits. Each array size was 100 mumx100 mum. A transverse-magnetic polarized wave in these metallic nanostructures generated resonant surface plasmons at a wavelength of about 800 nm in a water environment. Using the resonant wavelength shift in the nanoslit array, we achieved detection sensitivity up to 668 nm per refractive index unit, about 1.7 times larger than that reported on an array of nanoholes. An antigen-antibody interaction experiment in an aqueous environment verified the sensitivity in a surface binding event.

Molecular dynamics studies on the thermostability of family 11 xylanases.

Abstract: Twelve members of the family 11 xylanases, including both mesophilic and thermophilic proteins, were studied using molecular dynamics (MD). Simulations of xylanases were carried out in an explicit water environment at four different temperatures, 300, 400, 500 and 600 K. A difference in thermotolerance between mesophilic and thermophilic xylanases became clear: thermophilic xylanases endured heat in higher simulation temperatures better than mesophilic ones. The unfolding pathways seemed to be similar for all simulations regardless of the protein. The unfolding initiates at the N-terminal region or alternatively from the alpha-helix region and proceeds to the 'finger region'. Unfolding of these regions led to denaturated structures within the 4.5 ns simulation at 600 K. The results are in agreement with experimental mutant studies. The results show clearly that the stability of the protein is not evenly distributed over the whole structure. The MD analysis suggests regions in the protein structure which are more unstable and thus potential targets for mutation experiments to improve thermostability.

Stress Corrosion Cracking Behavior of Alloys in Aggressive Nuclear Reactor Core Environments

Abstract: The effects of irradiation on stress corrosion cracking occur through changes in the water chemistry and in the alloy microstructure. Considerable reactor experience has shown that a high-temperature water environment and a radiation field combine to produce irradiation-assisted stress corrosion cracking (IASCC) in core components of light water reactors. The principal effect of irradiation on water chemistry is through radiolysis, which results in an increase in the corrosion potential through the formation of radiolytic species consisting of radicals and molecules that can be oxidizing or reducing. In addition, profound effects of irradiation on the microchemistry and alloy microstructure create numerous pathways for IGSCC to occur. Radiation-induced segregation, the formation of a dislocation loop microstructure, irradiation hardening, and irradiation creep all occur simultaneously in space and time. Unfolding these various effects to determine the primary factors governing the observed effect...

Living Cities in Japan : Citizens' Movements, Machizukuri and Local Environments

Abstract: Introduction: Citizens' Movements, Machizukuri and Living Environments in Japan: A Shift Toward Local Empowerment? Part 1: Machizukuri and the Urban Context 1. Toshikeikaku versus Machizukuri 2. The Concept of Machisodate and Urban Planning 3. Machizukuri, Civil Society and the Transformation of Japanese City Planning: Cases from Kobe 4. Machizukuri and the Historical Identity in the Old City Center of Kobe 5. Reconstruction Machizukuri and Citizen Participation 6. Dividing the City: The Social Structure of Manshon Conflicts in Kyoto's Town Centre 7. Examining the Potential of Contemporary Art in Machizukuri Part 2: NPOs and the Environment 8. Comparing Policy-Networks: Climate Change Policies in Germany and Japan 9. Machizukuri in Contemporary Japan: What Role for the Non-Profit Sector 10. Japan's Construction Lobby Activities - Systemic Stability and Sustainable Regional Development 11. Citizens' Movements to Protect the Water Environment: Changes and Problems

Distal charge transport in peptides

Abstract: Biological systems often transport charges and reactive processes over substantial distances. Traditional models of chemical kinetics generally do not describe such extreme distal processes. In this Review, an atomistic model for a distal transport of information, which was specifically developed for peptides, is considered. Chemical reactivity is taken as the result of distal effects based on two-step bifunctional kinetics involving unique, very rapid motional properties of peptides in the subpicosecond regime. The bifunctional model suggests highly efficient transport of charge and reactivity in an isolated peptide over a substantial distance; conversely, a very low efficiency in a water environment was found. The model suggests ultrafast transport of charge and reactivity over substantial molecular distances in a peptide environment. Many such domains can be active in a protein.

Spatial planning, water and the Water Framework Directive: insights from theory and practice

Abstract: Water is fundamental to the health of the biosphere, strong economic growth and human social well-being. Despite its relative scarcity and absolute importance to life on earth, fresh water resources are often used inefficiently or polluted unnecessarily. Policymakers must work towards developing approaches to balance human demands for water with the water requirements of ecosystems. The European Water Framework Directive, which aims to encourage the sustainable management and protection of freshwater resources, brings this agenda into sharp focus in Europe. Land use change and environmental quality are closely related, and the nature and location of development can significantly influence both the generation and resolution of environmental problems. This places spatial planning, which provides a framework for regulating the development and use of land, in a strong position to affect water quantity and quality issues and thus to aid the achievement of the Directive's goals. In particular, spatial planning has an important function in integrating the use and management of land and water more closely than is presently the case. This paper explores the potential and actual role of spatial planning in addressing challenges associated with the water environment. This enables an assessment to be made of the extent to which spatial planning can help to meet the goals of the Water Framework Directive.

Preparation and properties of nano-sized Ag and Ag2S particles in biopolymer matrix

Abstract: Silver (Ag) and silver sulfide (Ag(2)S) nanoparticles were synthesized in a sago starch matrix The resulting nanocomposites were investigated using structural, optical and thermal methods XRD spectra of the nanocomposites confirmed the presence of nanostructured silver (cubic phase) and silver sulfide (monoclinic phase) in the matrix TEM micrographs showed that the nanoparticles are mostly spherical in shape Analyzes of the optical properties of the silver nanocomposite aqueous dispersions/solutions of various concentrations were carried out The results and the theoretical considerations suggested that at high concentrations there is a release of silver nanoparticles from the composite in the water environment Further dilution produces homogeneous solution in which silver nanoparticles are capped with starch macromolecules TGA analysis revealed reduced thermal stability of the nanocomposites with respect to pure starch matrix

Oxidative properties of FeO2+: electronic structure and solvation effects

Abstract: An electronic structure analysis is provided of the action of solvated FeO2+, [FeO(H2O)5]2+, as a hydroxylation catalyst. It is emphasized that the oxo end of FeO2+ does not form hydrogen bonds (as electron donor and H-bond acceptor) with H-bond donors nor with aliphatic C–H bonds, but it activates C–H bonds as an electron acceptor. It is extremely electrophilic, to the extent that it can activate even such poor electron donors as aliphatic C–H bonds, the C–H bond orbital acting as electron donor in a charge transfer type of interaction. Lower lying O–H bonding orbitals are less easily activated. The primary electron accepting orbital in a water environment is the 3σ*α orbital, an antibonding combination of Fe-3dz2 and O-2pz, which is very low-lying relative to the π*α compared with, for example, the σ* orbital in O2 relative to its π*. This is ascribed to relatively small Fe-3dz2 with O-2pz overlap, due to the nodal structure of the 3dz2.The H-abstraction barrier is very low in the gas phase, but it is considerably enhanced in water solvent. This is shown to be due to strong screening effects of the dielectric medium, leading to relative destabilization of the levels of the charged [FeO(H2O)5]2+ species compared to those of the neutral substrate molecules, making it a less effective electron acceptor. The solvent directly affects the orbital interactions responsible for the catalytic reaction.

A Novel Ferrofluidic Inclinometer

Abstract: Inertial transducers based on the use of ferrofluids as inertial mass can be of great interest due to their peculiarities and due to the advantages that they show when compared to traditional devices. Ferrofluids are special solutions of magnetic particles in a carrier liquid whose density and other physical features can be controlled by an external magnetic field. In this paper, the development of a ferrofluidic inclinometer, which exhibits a tunable operating range and a valuable metrological feature and an intrinsic robustness against inertial shocks, is presented. The device consists of one excitation coil and two sensing coils wound around a glass pipe where a drop of ferrofluid is contained in a water environment. The magnetic force, which is induced by the excitation coil, attracts the ferrofluidic mass in a position that depends on the device inclination. The voltage at the output of the two sensing coils is related to the ferrofluidic mass displacement and thus reflects the tilt to be measured. Analytical models, simulations, and experimental results are presented to demonstrate the suitability of the proposed approach.

Molecular Approaches and Breeding Strategies for Drought Tolerance in Barley

Abstract: Barley genotypes, in particular landraces and wild species, represent an important source of variation for adaptive traits that may contribute to increase yield and yield stability under drought conditions, and that could be introgressed into improved varieties. Traits that have been investigated include physiological/biochemical and developmental/ morphological traits. Yield performance under drought is particularly a complex phenomenon, and plants exhibit a diverse range of genetically complex mechanisms for drought resistance. Quantitative trait loci (QTL) studies with and without H. spontaneum have shown that developmental genes, notably those involved in flowering time and plant stature show pleiotropic effects on abiotic stress tolerance and ultimately determine yield. Problems associated with the hybridization of H. spontaneum such as alleles with deleterious effects on field performance could be best addressed in the advanced backcross (AB-) QTL analysis. It was interesting to see that in AB-QTL populations like in balanced populations major QTL overshadowed minor QTL-alleles. Nevertheless, crosses with H. spontaneum, AB-QTL populations and association studies with H. spontaneum have also identified new alleles and genes that are related to abiotic stress tolerance. In order to identify genes that are related to drought tolerance microarrays analysis to monitor gene expression profiles for plants exposed to limited water environment is performed. Several studies with rapid dehydration treatment have shown that osmotic-stress-inducible genes could explain the response to drought stress in plants. Another development is the identification and use of nucleotide polymorphisms (SNP) in genes related to abiotic stress tolerance. An understanding of the combined function and expression of genes involved in various abiotic stresses, could help identify candidate genes underlying QTL of interest.

Gravity Sanitary Sewer Design and Construction

Abstract: Prepared by a Joint Task Force of the Environment and Water Resources Institute and the Committee on Pipeline Planning of the Pipeline Division of ASCE and the Collection Systems Subcommittee of the Technical Practice Committee of the Water Environment Federation (WEF) Gravity Sanitary Sewer Design and Construction provides theoretical and practical guidelines for the design and construction of gravity sanitary sewers. This new edition covers the administrative and organizational phases of sanitary sewer projects, as well as the parameters necessary to establish the design criteria, complete the design, and award a construction contract. The manual offers an in-depth discussion of commonly used trenchless and conventional methods of sanitary sewer construction. With its liberal use of charts, illustrations, and case studies, this practical manual is an indispensable resource for engineers in the field of sanitary sewer structural and hydraulic design.

Human viruses in water

Abstract: This book provides overviews and updates on basic research, diagnosis, epidemiology, and public health on enteric viruses, as well as on treatment and intervention to prevent their waterborne transmission. Data are presented and interpreted by leading researchers in the field in 13 chapters. This title is an essential resource for virologists, epidemiologists, medical and public health professionals, graduate students and postdoctoral scientists at various levels of their careers. This title includes key topics such as: Ecology of enteric viruses; Intervention measures from risk assessment to virus disinfection practices; Cutting edge technology on procedures for virus detection and monitoring in water and the water environment; Quality assurance and quality control measures in water virology; and, Legal regulations regarding viruses in the environment.

Conformational study of the protegrin-1 (PG-1) dimer interaction with lipid bilayers and its effect

Abstract: Protegrin-1 (PG-1) is known as a potent antibiotic peptide; it prevents infection via an attack on the membrane surface of invading microorganisms. In the membrane, the peptide forms a pore/channel through oligomerization of multiple subunits. Recent experimental and computational studies have increasingly unraveled the molecular-level mechanisms underlying the interactions of the PG-1 β-sheet motifs with the membrane. The PG-1 dimer is important for the formation of oligomers, ordered aggregates, and for membrane damaging effects. Yet, experimentally, different dimeric behavior has been observed depending on the environment: antiparallel in the micelle environment, and parallel in the POPC bilayer. The experimental structure of the PG-1 dimer is currently unavailable. Although the β-sheet structures of the PG-1 dimer are less stable in the bulk water environment, the dimer interface is retained by two intermolecular hydrogen bonds. The formation of the dimer in the water environment implies that the pathway of the dimer invasion into the membrane can originate from the bulk region. In the initial contact with the membrane, both the antiparallel and parallel β-sheet conformations of the PG-1 dimer are well preserved at the amphipathic interface of the lipid bilayer. These β-sheet structures illustrate the conformations of PG-1 dimer in the early stage of the membrane attack. Here we observed that the activity of PG-1 β-sheets on the bilayer surface is strongly correlated with the dimer conformation. Our long-term goal is to provide a detailed mechanism of the membrane-disrupting effects by PG-1 β-sheets which are able to attack the membrane and eventually assemble into the ordered aggregates. In order to understand the dimeric effects leading to membrane damage, extensive molecular dynamics (MD) simulations were performed for the β-sheets of the PG-1 dimer in explicit water, salt, and lipid bilayers composed of POPC lipids. Here, we studied PG-1 dimers when organized into a β-sheet motif with antiparallel and parallel β-sheet arrangements in an NCCN packing mode. We focus on the conformations of PG-1 dimers in the lipid bilayer, and on the correlation between the conformations and the membrane disruption effects by PG-1 dimers. We investigate equilibrium structures of the PG-1 dimers in different environments in the early stage of the dimer invasion. The dimer interface of the antiparallel β-sheets is more stable than the parallel β-sheets, similar to the experimental observation in micelle environments. However, we only observe membrane disruption effects by the parallel β-sheets of the PG-1 dimer. This indicates that the parallel β-sheets interact with the lipids with the β-sheet plane lying obliquely to the bilayer surface, increasing the surface pressure in the initial insertion into the lipid bilayer. Recent experimental observation verified that parallel PG-1 dimer is biologically more active to insert into the POPC lipid bilayer.

Tubulin: from atomistic structure to supramolecular mechanical properties

Abstract: Microtubules (MTs) are fundamental structural elements in the cytoskeleton of eukaryotic cells. Their unique mechanical properties depend on the properties of the tubulin dimer, its interactions with surrounding dimers and the geometric organization within the MT. While the geometry has already been well described in experimental works, the mechanical characteristics of the dimer as well as of the individual monomers have up to date not been described. These may therefore provide new, additional insight to the microtubule tensile properties. In this paper we construct a mesoscale model of MT with a bottom-up approach. First, we evaluate the elastic constants of each of the two monomers together with the interaction force between them by means of molecular dynamics (MD) simulations carried out in an explicit water environment. Using the MD results, we model a 1 μm long MT as a cylinder constituted by interacting elastic elements and examine its properties via finite element method (FEM). The obtained results show an elastic constant value for α-tubulin of 11 N/m, while for the β-tubulin the elastic constant was measured to be 15.6 N/m. Concerning interactions between neighbouring monomers, the elastic constants along the protofilament (45 N/m for the intra-dimer interface and 18 N/m for the inter-dimer interface) are more rigid than elastic constants calculated for lateral interfaces (11 and 15 N/m). The mesoscale model provides mechanical properties of the whole MT, thus allowing the comparison with data obtained by other previous experimental and theoretical studies. We report here a Young modulus of 1.66 GPa for the MT under axial tension. In perspective our approach provides a simple tool for the analysis of MT mechanical behaviour under different conditions.

Stereo in-situ ecological urban water system repairing process

Abstract: The stereo in-situ ecological urban water system repairing process tackles polluted water via the quantitative analysis on the water The technological scheme includes physical simulation and mathematic model analysis, microbe inoculation and culture, constituting refluxing ecological filter bed, purification with biocarrier, artificial aeration, purifying upper water, pre-treatment in the blow down port, establishing water ecological system balance, perfecting water environment data, etc The present invention realizes the comprehensive tackling of urban water system

SCC of cold-worked austenitic stainless steels in PWR conditions

Abstract: Solution annealed austenitic stainless steels, essentially of type AISI 304(L) and AISI 316(L), were originally considered not susceptible to cracking by SCC in the reducing environment of PWRs primary water. However, Constant Extension Rate Tests (CERTs), performed on heavily cold worked austenitic stainless steels specimens have demonstrated that these materials can exhibit clear SCC cracking susceptibility with fast intergranular or transgranular crack growth. Careful examination of the austenitic stainless steels susceptibility conditions to cracking have shown that work hardening under restricted conditions can promote SCC in PWR conditions. The respective influence of various cold working modes (shot peening, cold rolling, fatigue work hardening, milling and tensile deformation) is investigated by means of screening CERTs performed essentially on 304L in simulated PWRs primary water at 320°C and 360°C. The effect of dissolved hydrogen level on the materials susceptibility to cracking is examined via dedicated tests at 320°C. For a given cold work hardening level, the susceptibility to crack initiation strongly depends on the cold working process and no propagation is observed for a hardness level lower than 300 10 HV(0.49N). The propagation of cracks appears to be strongly connected with dynamic loading conditions associated with CERT, tension tests and crack growth propagation tests performed on CT specimens under cyclic loading. Indeed, although shallow crack initiation is observed for constant load, crack propagation does not occur under strict static loading conditions during a long term 17,000 hours SCC test, even for initial material hardness levels higher than 450 HV(0.49N). On the basis of existing references, the presence of significant levels of atomic hydrogen inside coldworked austenitic stainless steels as a consequence of long duration exposure to reducing PWRs conditions can be assumed. The role of interstitial hydrogen on the process of cracking is questioned. Dedicated experiments carried out on 304L stainless steel have shown that atomic hydrogen present inside cold-worked austenitic stainless steels can under some conditions promote occurrence of limited H-induced embrittlement cracking phenomena in the low temperature range (tests performed at ambient temperature and 140°C). This process should be considered in the context of the evaluation of crack initiation susceptibility of 304L austenitic stainless steel exposed to primary water environment. Introduction Susceptibility of sensitized austenitic stainless steels to SCC is a well known phenomenon identified in BWR oxidizing environments. Long term research carried out in the case of BWR-type conditions have shown certain minimum levels of chloride and oxygen are required for SCC susceptibility [1 4]. The detrimental role of cold-work on the resistance of austenitic stainless steels to SCC was also clearly recognized in pure water BWR-type conditions in the presence of limited amounts of oxygen [5 9]. Cold-work was generally identified to increase Crack Growth Rates (CGR) and reduce the estimated crack initiation time for austenitic stainless steels tested in pure water containing oxygen at a temperature around 300°C. The electrochemical potential usually measured for austenitic stainless steels exposed to hydrogenated PWR conditions appears well below the critical potential recognized for SCC initiation and too low to promote SCC susceptibility of these materials in absence of a significant amount of specific impurities. Consequently, solution annealed austenitic stainless steels, essentially of type AISI 304(L) and AISI 316(L), are generally considered as immune to SCC in hydrogenated primary water and these materials are thus widely used in PWRs. Some rather recent data [10, 11] have however demonstrated that austenitic stainless steels specimens that were severely cold-worked (samples incorporated a cold deformed hump) were susceptible to SCC in hydrogenated PWR environment under CERTs conditions. Crack propagation was similarly observed on pre-strained, unsensitized austenitic stainless steels in pure water containing hydrogen despite the low electrochemical potential measured during the experiments [8]. The resistance of austenitic stainless steels to SCC in PWR conditions should be therefore re-evaluated with regard to the potential specific effects of cold-work. The objective of this paper is to detail the results obtained in the framework of the CEA-EDF research program dealing with SCC of cold-worked austenitic stainless steels. The main focus of this program is to assess SCC initiation susceptibility of steels considering the respective effects of cold-working mode and environmental parameters derived from standard PWR conditions. Experimental procedure

Hot spot occlusion from bulk water: a comprehensive study of the complex between the lysozyme HEL and the antibody FVD1.3.

Abstract: Alanine scanning of protein-protein interfaces has shown that there are some residues in the protein-protein interfaces, responsible for most of the binding free energy, which are called hot spots. Hot spots tend to exist in densely packed central clusters, and a hypothesis has been proposed that considers that inaccessibility to the solvent must be a necessary condition to define a residue as a binding hot spot. This O-ring hypothesis is mainly based on the analysis of the accessible surface area (ASA) of 23 static, crystallographic structures of protein complexes. It is known, however, that protein flexibility allows for temporary exposures of buried interfacial groups, and even though the ASA provides a general trend of the propensity for hydration, protein/solvent-specific interactions or hydrogen bonding cannot be considered here. Therefore, a microscopic level, atomistic picture of hot spot solvation is needed to support the O-ring hypothesis. In this study, we began by applying a computational alanine-scanning mutagenesis technique, which reproduces the experimental results and allows for decomposing the binding free energy difference in its different energetic factors. Subsequently, we calculated the radial distribution function and residence times of the water molecules near the hot/warm spots to study the importance of the water environment around those energetically important amino acid residues. This study shows that within a flexible, dynamic protein framework, the warm/hot spot residues are, indeed, kept sheltered from the bulk solvent during the whole simulation, which allows a better interacting microenvironment.

Coordinated Transport by Multiple Biomimetic Robotic Fish in Underwater Environment

Abstract: This paper presents a coordination method for multiple biomimetic robotic fish in underwater transport task. Based on our robotic fish prototype, we further investigate the coordination problems of multiple robotic fish. Considering the kinematic constraints of the robotic fish, and the unstructured and dynamic characteristics of the water environment, we utilize the limit cycle approach to control the posture of the fish and realize collision avoidance. To control the transport orientation in the particular underwater environment, the fuzzy logic method is adopted. Experimental results of transportation performed by three robotic fish validate the effectiveness of the proposed method.