Tapping wave energy through Longuet-Higgins microseism effect

International audienceIt is well-known, since the works of Miche (1944) and Longuet-Higgins (1950), that, under a standing wave system, second-order pressures at twice the wave frequency penetrate the water column down to the sea-°oor, whatever the waterdepth. Recently Gu¶evel proposed that energy could be extracted from the waves with a heaving horizontal plate at the sea bottom, located next to a re°ective cli® or sea-wall, and tuned to oscillate at twice the wave frequency. Encouraging preliminary experiments were conducted in ACRI's wavetank (Lajoie et al. 2007). In this paper we address the theoretical modeling of wave energy extraction with such a device, in the asymptotic case when the waterdepth is very large compared to the wavelength. In section I we assume that the ¯rst-order wave system is little modi¯ed, i.e. the power taken from the waves is a small portion of the power carried by the incoming wave. In section II we relieve this assumption and we show that one hundred percent of the wave power can be extracted, notwithstanding how large the waterdepth

Proteins to Order Use of Synthetic DNA to Generate Site-Specific Mutations

The ability to cause specific changes in the amino acid sequences of proteins would greatly advance studies on the influence of protein structure on biochemical function. If the desired changes can once be made in the nucleic acid which encodes the protein, one can use cloning in an appropriate microorganism to produce essentially limitless quantities of the mutant protein. We describe here the application of oligonucleotide-directed site-specific mutagenesis to accomplish this objective for the enzyme B-lactamase, the gene for which is contained in the plasmid pBR322. The method uses a procedure to screen for mutant clones which depends on the DNA in the various colonies and not on the properties of the mutant protein; the method can, therefore, be widely applied and does not require, in each separate case, the development of a screening procedure which depends on some phenotypic difference between mutant and wild-type protein

55 Investigation of the RetS–GacAS regulatory network in clinical Pseudomonas aeruginosa isolates reveals evolutionary adaptation

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Ativação alcalina de cinzas volantes utilizando solução combinada de NaOH e Ca(OH)2

Este trabalho teve como objetivo avaliar o comportamento da resistência à compressão, ao longo do tempo, em amostras de argamassas à base de cinzas volantes álcali-ativadas. Como ativador alcalino foi utilizada uma solução combinada de NaOH e Ca(OH)2. A cura das amostras foi realizada de duas formas distintas. Na primeira, as amostras foram mantidas em estufa à 70°C/12 hs e à temperatura constante de 22°C em sala climatizada até a idade de ensaio. Apesar de serem obtidas resistências da ordem de 20 MPa nas primeiras 24 hs, houve decréscimo da resistência a partir da idade de 7 dias. Verificado esse comportamento, um segundo método de cura foi adotado. Para isso, o traço utilizado para o preparo de novas argamassas foi o mesmo adotado no método anterior. Porém, foram submetidas à temperatura constante de 70°C até a idade de ensaio. Nesse caso, as amostras apresentaram decréscimo mais acentuado da resistência em menor espaço de tempo, quando comparado às amostras curadas no primeiro método. Como estudos complementares foram realizadas análises microestruturais da CV antes e depois da ativação, utilizando o MEV/EDS.The main objective of this work was to evaluate the development of the compressive strength, along time, in alkali-activated fly ash mortars. As alkaline activator a combined solution of NaOH and Ca(OH)2 was used. The cure of the samples was carried through two distinct forms. In the first one, samples were kept in oven at 70°C during the first 12 hours and at constant room temperature of 22°C afterwards, until the age of testing. Compressive strength of 20 MPa magnitude were achieved during the first 24 hours, however it started to decrease after the age of 7 days. Considering this behaviour, second method of curing was adopted for the same mixing proportions. However, mortar samples were kept in oven at 70°C until the age of testing. In this case, compressive strength results decreased more significantly and at earlier ages, when compared with the results of samples cured using the first method. As complementary to understand the decreasing in compressive strength, microstructural analyses of the fly ash, before and after the activation, have been carried out, using the SEM/EDS

Particulate Matter Air Pollution Exposure, Distance to Road, and Incident Lung Cancer in the Nurses’ Health Study Cohort

Background: A body of literature has suggested an elevated risk of lung cancer associated with particulate matter and traffic-related pollutants. Objective: We examined the relation of lung cancer incidence with long-term residential exposures to ambient particulate matter and residential distance to roadway, as a proxy for traffic-related exposures. Methods: For participants in the Nurses’ Health Study, a nationwide prospective cohort of women, we estimated 72-month average exposures to PM2.5, PM2.5–10, and PM10 and residential distance to road. Follow-up for incident cases of lung cancer occurred from 1994 through 2010. Cox proportional hazards models were adjusted for potential confounders. Effect modification by smoking status was examined. Results: During 1,510,027 person-years, 2,155 incident cases of lung cancer were observed among 103,650 participants. In fully adjusted models, a 10-μg/m3 increase in 72-month average PM10 [hazard ratio (HR) = 1.04; 95% CI: 0.95, 1.14], PM2.5 (HR = 1.06; 95% CI: 0.91, 1.25), or PM2.5–10 (HR = 1.05; 95% CI: 0.92, 1.20) was positively associated with lung cancer. When the cohort was restricted to never-smokers and to former smokers who had quit at least 10 years before, the associations appeared to increase and were strongest for PM2.5 (PM10: HR = 1.15; 95% CI: 1.00, 1.32; PM2.5: HR = 1.37; 95% CI: 1.06, 1.77; PM2.5–10: HR = 1.11; 95% CI: 0.90, 1.37). Results were most elevated when restricted to the most prevalent subtype, adenocarcinomas. Risks with roadway proximity were less consistent. Conclusions: Our findings support those from other studies indicating increased risk of incident lung cancer associated with ambient PM exposures, especially among never- and long-term former smokers. Citation: Puett RC, Hart JE, Yanosky JD, Spiegelman D, Wang M, Fisher JA, Hong B, Laden F. 2014. Particulate matter air pollution exposure, distance to road, and incident lung cancer in the Nurses’ Health Study Cohort. Environ Health Perspect 122:926–932; http://dx.doi.org/10.1289/ehp.130749

The effect of local thermal fluctuations on the folding kinetics: a study from the perspective of the nonextensive statistical mechanics

Protein folding is a universal process, very fast and accurate, which works consistently (as it should be) in a wide range of physiological conditions. The present work is based on three premises, namely: ($i$) folding reaction is a process with two consecutive and independent stages, namely the search mechanism and the overall productive stabilization; ($ii$) the folding kinetics results from a mechanism as fast as can be; and ($iii$) at nanoscale dimensions, local thermal fluctuations may have important role on the folding kinetics. Here the first stage of folding process (search mechanism) is focused exclusively. The effects and consequences of local thermal fluctuations on the configurational kinetics, treated here in the context of non extensive statistical mechanics, is analyzed in detail through the dependence of the characteristic time of folding ($\tau$) on the temperature $T$ and on the nonextensive parameter $q$.The model used consists of effective residues forming a chain of 27 beads, which occupy different sites of a $3-$D infinite lattice, representing a single protein chain in solution. The configurational evolution, treated by Monte Carlo simulation, is driven mainly by the change in free energy of transfer between consecutive configurations. ...Comment: 19 pages, 3 figures, 1 tabl

Effect of Gypsum on the Early Hydration of Cubic and Na-Doped Orthorhombic Tricalcium Aluminate

The tricalcium aluminate (C3A) and sulfate content in cement influence the hydration chemistry, setting time and rheology of cement paste, mortar and concrete. Here, in situ experiments are performed to better understand the effect of gypsum on the early hydration of cubic (cub-)C3A and Na-doped orthorhombic (orth-)C3A. The isothermal calorimetry data show that the solid-phase assemblage produced by the hydration of C3A is greatly modified as a function of its crystal structure type and gypsum content, the latter of which induces non-linear changes in the heat release rate. These data are consistent with the in situ X-ray diffraction results, which show that a higher gypsum content accelerates the consumption of orth-C3A and the subsequent precipitation of ettringite, which is contrary to the cub-C3A system where gypsum retarded the hydration rate. These in situ results provide new insight into the relationship between the chemistry and early-age properties of cub- and orth-C3A hydration and corroborate the reported ex situ findings of these systems