Location and Conformation of the LK alpha 14 Peptide in Water/Ethanol Mixtures

It is widely recognized that solvation is one of the major factors determining structure and functionality of proteins and long peptides, however it is a formidable challenge to address it both experimentally and computationally. For this reason, simple peptides are used to study fundamental aspects of solvation. It is well established that alcohols can change the peptide conformation and tuning of the alcohol content in solution can dramatically affect folding and, as a consequence, the function of the peptide. In this work, we focus on the leucine and lysine based LK alpha 14 peptide designed to adopt an alpha-helical conformation at an apolar-polar interface. We investigate LK alpha 14 peptide's bulk and interfacial behavior in water/ethanol mixtures combining a suite of experimental techniques (namely, circular dichroism and nuclear magnetic resonance spectroscopy for the bulk solution, surface pressure measurements and vibrational sum frequency generation spectroscopy for the air-solution interface) with molecular dynamics simulations. We observe that ethanol highly affects both the peptide location and conformation. At low ethanol content LK alpha 14 lacks a clear secondary structure in bulk and shows a clear preference to reside at the air-solution interface. When the ethanol content in solution increases, the peptide's interfacial affinity is markedly reduced and the peptide approaches a stable alpha-helical conformation in bulk facilitated by the amphiphilic nature of the ethanol molecules

Assessing the vulnerability of buildings to tsunami in Sydney

Australia is vulnerable to the impacts of tsunamis and exposure along the SE coast of New South Wales is especially high. Significantly, this is the same area reported to have been affected by repeated large magnitude tsunamis during the Holocene. Efforts are under way to complete probabilistic risk assessments for the region but local government planners and emergency risk managers need information now about building vulnerability in order to develop appropriate risk management strategies. We use the newly revised PTVA-3 Model (Dall'Osso et al., 2009) to assess the relative vulnerability of buildings to damage from a "worst case tsunami" defined by our latest understanding of regional risk – something never before undertaken in Australia. We present selected results from an investigation of building vulnerability within the local government area of Manly – an iconic coastal area of Sydney. We show that a significant proportion of buildings (in particular, residential structures) are classified as having "High" and "Very High" Relative Vulnerability Index scores. Furthermore, other important buildings (e.g., schools, nursing homes and transport structures) are also vulnerable to damage. Our results have serious implications for immediate emergency risk management, longer-term land-use zoning and development, and building design and construction standards. Based on the work undertaken here, we recommend further detailed assessment of the vulnerability of coastal buildings in at risk areas, development of appropriate risk management strategies and a detailed program of community engagement to increase overall resilience

Corrigendum to "A revised (PTVA) model for assessing the vulnerability of buildings to tsunami damage" published in Nat. Hazards Earth Syst. Sci., 9, 1557–1565, 2009"

No abstract available

Comunità microbica associata a Hyalesthes obsoletus Signoret, vettore del Legno nero della vite

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Optical absorption and photoluminescence spectroscopy of the growth of silver nanoparticles

Results obtained from the optical absorption and photoluminescence (PL) spectroscopy experiments have shown the formation of excitons in the silver-exchanged glass samples. These findings are reported here for the first time. Further, we investigate the dramatic changes in the photoemission properties of the silver-exchanged glass samples as a function of postannealing temperature. Observed changes are thought to be due to the structural rearrangements of silver and oxygen bonding during the heat treatments of the glass matrix. In fact, photoelectron spectroscopy does reveal these chemical transformations of silver-exchanged soda glass samples caused by the thermal effects of annealing in a high vacuum atmosphere. An important correlation between temperature-induced changes of the PL intensity and thermal growth of the silver nanoparticles has been established in this Letter through precise spectroscopic studies.Comment: 15 pages,4 figures,PDF fil

String tension in gonihedric 3D Ising models

For the 3D gonihedric Ising models defined by Savvidy and Wegner the bare string tension is zero and the energy of a spin interface depends only on the number of bends and self-intersections, in antithesis to the standard nearest-neighbour 3D Ising action. When the parameter kappa weighting the self-intersections is small the model has a first order transition and when it is larger the transition is continuous. In this paper we investigate the scaling of the renormalized string tension, which is entirely generated by fluctuations, using Monte Carlo simulations This allows us to obtain an estimate for the critical exponents alpha and nu using both finite-size-scaling and data collapse for the scaling function.Comment: Latex + postscript figures. 8 pages text plus 7 figures, spurious extra figure now removed

Uniaxial magnetic anisotropy tuned by nanoscale ripple formation: ion-sculpting of Co/Cu(001) thin films

We have investigated the growth of surface nanostructures on a Co/Cu(001) film and the growth of Co films on a nanostructured Cu(001) substrate as well as the effect of nanoscale pattern formation on the film magnetic properties. Here we demonstrate by scanning tunneling microscopy measurements and magneto-optic Kerr effect hysteresis curves that low-temperature grazing-incidence ion sputtering can be used to induce the formation of nanoscale ripples which reduce the four-fold symmetry of the Co film to two-fold, thus generating a strong in-plane uniaxial magnetic anisotropy. The nanostructures and the associated uniaxial magnetic anisotropy were found to be stable up to room temperature

Study of the bacterial community affiliated to Hyalesthes obsoletus, the insect vector of “bois noir” phytoplasma of grape

Grape yellows caused by phytoplasmas afflict several important wine-producing areas of Europe. A grape yellows with increasingincidence in European vineyards is “bois noir” (BN), caused by ‘Candidatus Phytoplasma solani’. Its vector is the planthopperHyalesthes obsoletus Signoret (Hemiptera Cixiidae), occasionally feeding on grapevine. An innovative strategy for reducing thediffusion of the disease could be symbiotic control, exploiting the action of symbiotic microorganisms of the insect host. To investigatethe occurrence of possible microbial candidates for symbiotic control we performed a molecular characterization of thebacteria associated to H. obsoletus. Length heterogeneity PCR was applied for a preliminary population screening. Taxonomicaffiliations of the bacterial species were analyzed by denaturing gradient gel electrophoresis, showing, within the microbial diversity,the intracellular reproductive parasite Wolbachia pipientis and a Bacteroidetes symbiont with 92% nt identity with ‘CandidatusSulcia muelleri’. PCR essays specific for these bacteria showed they co-localize in several organs of H. obsoletus. Fluorescentin situ hybridization was performed to assess the distribution of these microorganisms within the insect body, showing interestinglocalization patterns, particularly in insect gonads and salivary glands. These results could be a starting point for a deeper investigationof functions and relationships between microbial species