Corrosion reduction of aluminum alloys in flowing high-temperature water

Report describes a technique for reducing the corrosion rate of aluminum by adding colloidal substances in a closed-loop system. Experimental work shows that the addition of graphite and colloidal hydrated aluminum oxide significantly reduces the corrosion rate in flowing high-temperature water

Best practice in undertaking and reporting health technology assessments : Working Group 4 report

[Executive Summary] The aim of Working Group 4 has been to develop and disseminate best practice in undertaking and reporting assessments, and to identify needs for methodologic development. Health technology assessment (HTA) is a multidisciplinary activity that systematically examines the technical performance, safety, clinical efficacy, and effectiveness, cost, costeffectiveness, organizational implications, social consequences, legal, and ethical considerations of the application of a health technology (18). HTA activity has been continuously increasing over the last few years. Numerous HTA agencies and other institutions (termed in this report “HTA doers”) across Europe are producing an important and growing amount of HTA information. The objectives of HTA vary considerably between HTA agencies and other actors, from a strictly political decision making–oriented approach regarding advice on market licensure, coverage in benefits catalogue, or investment planning to information directed to providers or to the public. Although there seems to be broad agreement on the general elements that belong to the HTA process, and although HTA doers in Europe use similar principles (41), this is often difficult to see because of differences in language and terminology. In addition, the reporting of the findings from the assessments differs considerably. This reduces comparability and makes it difficult for those undertaking HTA assessments to integrate previous findings from other HTA doers in a subsequent evaluation of the same technology. Transparent and clear reporting is an important step toward disseminating the findings of a HTA; thus, standards that ensure high quality reporting may contribute to a wider dissemination of results. The EUR-ASSESS methodologic subgroup already proposed a framework for conducting and reporting HTA (18), which served as the basis for the current working group. New developments in the last 5 years necessitate revisiting that framework and providing a solid structure for future updates. Giving due attention to these methodologic developments, this report describes the current “best practice” in both undertaking and reporting HTA and identifies the needs for methodologic development. It concludes with specific recommendations and tools for implementing them, e.g., by providing the structure for English-language scientific summary reports and a checklist to assess the methodologic and reporting quality of HTA reports

Electromechanical Reliability Testing of Three-Axial Silicon Force Sensors

This paper reports on the systematic electromechanical characterization of a new three-axial force sensor used in dimensional metrology of micro components. The siliconbased sensor system consists of piezoresistive mechanicalstress transducers integrated in thin membrane hinges supporting a suspended flexible cross structure. The mechanical behavior of the fragile micromechanical structure isanalyzed for both static and dynamic load cases. This work demonstrates that the silicon microstructure withstands static forces of 1.16N applied orthogonally to the front-side of the structure. A statistical Weibull analysis of the measured data shows that these values are significantly reduced if the normal force is applied to the back of the sensor. Improvements of the sensor system design for future development cycles are derived from the measurement results.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Raman microscopy of lithium-manganese-rich transition metal oxide cathodes

Lithium-rich and manganese-rich (LMR) layered transition metal (TM) oxide composites with general formula xLi2MnO3 • (1- x)LiMO2 (M = Ni, Co, Mn) are promising cathode candidates for high energy density lithium ion batteries. Lithium-manganese-rich TM oxides crystallize as a nanocomposite layered phase whose structure further evolves with electrochemical cycling. Raman spectroscopy is a powerful tool to monitor the crystal chemistry and correlate phase changes with electrochemical behavior. While several groups have reported Raman spectra of lithium rich TM oxides, the data show considerable variability in terms of both the vibrational features observed and their interpretation. In this study, Raman microscopy is used to investigate lithium-rich and manganese-rich TM cathodes as a function of voltage and electrochemical cycling at various temperatures. No growth of a spinel phase is observed within the cycling conditions. However, analysis of the Raman spectra does indicate the structure of LMR-NMC deviates significantly from an ideal layered phase. The results also highlight the importance of using low laser power and large sample sizes to obtain consistent data sets

Courtship pheromones in parasitic wasps: comparison of bioactive and inactive hydrocarbon profiles by multivariate statistical methods

Cuticular hydrocarbons play a significant role in the regulation of cuticular permeability and also in the chemical communication of insects. In the parasitoid Lariophagus distinguendus (Hymenoptera: Pteromalidae), male courtship behavior is mediated by a female-produced sex pheromone. Previous studies have shown that the chemicals involved are already present in the pupal stage of both males and females. However, pheromonal activity in males decreases shortly after emergence. This pheromonal deactivation occurs only in living males, suggesting an active process rather than simple evaporation of bioactive compounds. Here, we present evidence that the sex pheromone of L. distinguendus is composed of a series of cuticular hydrocarbons. Filter paper disks treated with nonpolar fractions of cuticular extracts of freshly emerged males and females, 72-hr-old females, and yellowish pupae caused arrestment and stimulated key elements of courtship behavior in males, whereas fractions of 72-hr-old males did not. Sixty-four hydrocarbons with chain length between C25 and C37 were identified in the fractions by gas chromatography-mass spectrometry (GC-MS). Methyl-branched alkanes with one to four methyl groups were major components, along with traces of n-alkanes and monoalkenes. Principal component analysis, based on the relative amounts of the compounds, revealed that cuticular hydrocarbon composition differed among all five groups. By using partial least squares-discriminant analysis, we determined a series of components that differentiate bioactive and bioinactive hydrocarbon profiles, and may be responsible for pheromonal activity of hydrocarbon fractions in L. distinguendus

Corrosion of Some Reactor Materials in Dilute Phosphoric Acid

Corrosion tests in dilute phosphoric acid (pH 3.5) at elevated temperature are described for X8001 aluminum, 18-8 stainless steels, aluminized carbon steel, and Zircaloy. In a 307-day dynamic test at 18 ft/sec and 315 deg C, X8001 aluminum corroded at a rate of 1/2 mdd for the first 240 days. In subsequent exposures, the corrosion rate increased, but the total average penetration at 307 days was only 0.0005 inch. At 200 days, the total corrosion in this test was one-fiftieth that in distilled water. Static tests at 225 deg C gave corrosion rates too low to measure (<0.2 mdd). Of several different 18-8 stainless steels tested in this solution at 315 deg C, only sensitized type 316 suffered intergranular attack. General attack rates of the other samples, of the order of 1/4 mdd, were obtained for the period from 94 to 186 days. Although this is much larger than the rate in distilled water, it represents a penetration rate of only about 5 x 10/sup -//sup 5/ inch/year. Aluminized carbon steel did not suffer rapid corrosion in this solution at 315 deg C, even when large areas of the carbon steel were exposed. There was a tendency for corrosion to separate the steel and aluminum with some specimens, depending on the heat treatment. Zircaloy-2 and Zircaloy-3 corrosion were of the same order in this solution at 315 deg C as in water. (auth

CORROSION OF SOME REACTOR MATERIALS IN DILUTE PHOSPHORIC ACID

Corrosion tests in dilute phosphoric acid (pH 3.5) at elevated temperature are described for X8001 aluminum, 18-8 stainless steels, aluminized carbon steel, and Zircaloy. In a 307-day dynamic test at 18 ft/sec and 315 deg C, X8001 aluminum corroded at a rate of 1/2 mdd for the first 240 days. In subsequent exposures, the corrosion rate increased, but the total average penetration at 307 days was only 0.0005 inch. At 200 days, the total corrosion in this test was one-fiftieth that in distilled water. Static tests at 225 deg C gave corrosion rates too low to measure (<0.2 mdd). Of several different 18-8 stainless steels tested in this solution at 315 deg C, only sensitized type 316 suffered intergranular attack. General attack rates of the other samples, of the order of 1/4 mdd, were obtained for the period from 94 to 186 days. Although this is much larger than the rate in distilled water, it represents a penetration rate of only about 5 x 10/sup -//sup 5/ inch/year. Aluminized carbon steel did not suffer rapid corrosion in this solution at 315 deg C, even when large areas of the carbon steel were exposed. There was a tendency for corrosion to separate the steel and aluminum with some specimens, depending on the heat treatment. Zircaloy-2 and Zircaloy-3 corrosion were of the same order in this solution at 315 deg C as in water. (auth

CORROSION OF ALUMINUM AND ITS ALLOYS IN SUPERHEATED STEAM

The corrosion behavior of pure aluminum and some of its alloys in superheated steam was found to depend markedly on the method of starting the corrosion test. Pure aluminum samples survived only in tests that were brought to temperature and pressure very rapidly. Resistant Al-- Ni-- Fe alloys performed well only if a relatively slow starting procedure was used, suffering extensive blistering or complete disintegration in a test started rapidly. Over the range of temperature and pressure investigated, 400 to 540 deg C and 150 to 600 psig, with optimum starting conditions both pure aluminum and resistant Al-- Ni-- Fe alloy samples quickly formed a very protective oxide film. Interference colors were noted for exposures of several weeks. Samples surviving a 260-day test at 540 deg C and 600 psig had less than 1-mg/cm/sup 2/ weight gain. Nonresistant alloys disintegrated in short corrosion exposures. A penetrating attack, initiated in only a few spots, rapidly destroyed the samples. The effects of composition, dispersion of second-phsse compounds, hydrogen porosity, and pretreatments were investigated for 5.6% Ni--0.3% Fe-0.1% Ti in 540 deg C, 600-psig steam. It was concluded that porosity produced by corrosion product hydrogen was a major factor in the survival of samples. A mechanism for the rapid penetrating attack was proposed as based on observations made during the study of hydrogen porosity. Pretreatment of resistant alloy samples in dry air at 540 deg C or in high-temperature water at 350 deg C greatly reduced the amount of porosity produced by corrosion in superheated steam. (auth

Electronic structure of Fe- vs. Ru-based dye molecules

In order to explore whether Ru can be replaced by inexpensive Fe in dye molecules for solar cells, the differences in the electronic structure of Fe- and Ru-based dyes are investigated by X-ray absorption spectroscopy and first-principles calculations. Molecules with the metal in a sixfold, octahedral N cage, such as tris(bipyridines) and tris(phenanthrolines), exhibit a systematic downward shift of the N 1s-to-π* transition when Ru is replaced by Fe. This shift is explained by an extra transfer of negative charge from the metal to the N ligands in the case of Fe, which reduces the binding energy of the N 1s core level. The C 1s-to-π* transitions show the opposite trend, with an increase in the transition energy when replacing Ru by Fe. Molecules with the metal in a fourfold, planar N cage (porphyrins) exhibit a more complex behavior due to a subtle competition between the crystal field, axial ligands, and the 2+ vs. 3+ oxidation states.This work was supported by the National Science Foundation (NSF) under Award Nos. CHE-1026245, DMR-1121288 (MRSEC), DMR-0537588 (SRC), and by the (U.S.) Department of Energy (DOE) under Contract Nos. DE-FG02-01ER45917 (end station) and DE-AC02-05CH11231 (ALS). P. L. Cook acknowledges support from the University of Wisconsin System 2012-2013 Applied Research Grant. J. M. García-Lastra and A. Rubio acknowledge financial support from the European Research Council (ERC-2010-AdG-Proposal No. 267374), Spanish Grants (FIS2011-65702-C02-01 and PIB2010US-00652), Grupos Consolidados (IT-319-07), and European Commission project CRONOS (280879-2).Peer Reviewe