Distribution and origin of major and trace elements (particularly REE, U and Th) into labile and residual phases in an acid soil profile (Vosges Mountains, France).

A seven step sequential extraction procedure has been conducted on a podzolic soil profile from the Vosges Mountains in order to determine the ability of several elements to be released to the environment. Very little Si, K and Al were extractable ( 10% of the total soil concentration) of Ca, P, metals (Fe, Pb), REE and actinides (Th, U) could be leached. For each element, preferential binding sites can be recognized. High recovery of P and Ca in the acid soluble fraction (AS) suggests that phosphate minerals are highly involved in this step of the extraction. Organic matter appears to control the adsorption of Ca, Fe, Th, U and REE, even at depths in the soil profile where organic matter content is particularly low (0.5%). Weak acid leaching experiments (with HCl and acid acetic 0.001 N) were also performed in order to characterize the origin of the insoluble material in this soil profile. The leachable REE distributions indicate that a large part of the labile REE in the surface horizon has an atmospheric origin whereas at greater depth phosphate mineral (apatite) alteration is the main factor controlling REE release in the leachate. Our study further suggests that adsorbed material holding actinides and REE are not strictly the same. So, caution should be taken when using REE as analogues for actinides in soils systems

REE fractionation during granite weathering and removal by waters and suspended loads: Sr and Nd isotopic evidence

Very few studies deal with REE (rare earth element) mobility within the system soil–soil solution–streamwater. In this article, we try to characterize the fractionation and the migration of the REE in a granite-derived soil system located in a small catchment of the Vosges mountains. ICP-MS and TIMS measurements were performed on both solid samples (“fresh” granite, soil, and suspended load of the stream) and waters (soil solutions, springwater, and streamwater) to determine their respective REE concentrations and Sr and Nd isotopic compositions. The PAAS-normalized REE pattern of the bedrock is characterized by a strong depletion in HREE (heavy REE) and a negative Eu anomaly (0.46). Similarly, the granite-normalized REE distribution patterns of the soil samples show HREE depletions that become more important with decreasing depth. The correlative behavior between P2O5, Th, and REE with depth indicates that, besides apatite, other phosphate minerals such as monazite are the most important phases controlling the Th and REE budget in the soil profile. On the other hand, at greater depth, zircon seems to be another important mineral phase controlling especially the HREE enrichment as shown by the positive relationship between Zr content and the Yb/Ho ratio. Different grain size fractions show similar REE distribution patterns and are only weakly fractionated, compared with bulk soil sample. However, the finest fraction (0–20 mm) is more enriched in Sr and REE, suggesting a stronger concentration of REE-carrying minerals in this fraction. The suspended and dissolved load of the stream show as a whole an enrichment in HREE if compared with the granite or with the different soil samples. However, compared with the uppermost soil samples, the suspended load is significantly more enriched in HREE. Its REE distribution pattern is more similar to that of the finest fraction of the deeper soil sample and to the “fresh” granite. Thus, most probably the REE of the suspended load originated from a source with REE characteristics found in the deep soil horizons. This source might have been situated in the uppermost soil profile, which is actually REE depleted. The weathering process can be compared with a leaching experiment where the waters correspond to the leachate and the soil to the residual phase of the granite. The Sr isotope data indicate that the suspended load originates from the finest soil fraction. The Sr and Nd isotopic data of the suspended load suggest that it contains up to 3% Sr and Nd from apatite and up to 97% from feldspar. Most of the Sr and Nd in the waters originate from apatite leaching or dissolution

The Monterey event in the Mediterranean: A record from shelf sediments of Malta

Oligo-Miocene carbonate platform and shelf sediments outcropping on the Maltese Islands provide an excellent archive of the paleoceanography of the central Mediterranean. A sequence of shallow water limestones, than shelf limestones, and marls, followed again by shallow water limestones, reflects drowning of a carbonate platform, the establishment of a shelf environment and, in the late Miocene, renewed progradation and aggradation of shallow water carbonates. The sequence recording the deepening of the Maltese platform contains several phosphorite hardgrounds and phosphorite pebble beds. These phosphorites were dated with strontium isotopes. Major episodes of phosphogenesis occurred between 25 and 16 Ma, and they are coeval with those phosphorite events reported from Florida and North Carolina. A Miocene carbon isotope and oxygen isotope stratigraphy was established on planktic and benthic foraminifera and on bulk samples. A major carbon isotope excursion with an amplitude of up to +l‰ between 18 and 12.5 Ma can be correlated with the globally recognized Monterey carbon isotope excursion. This is the first record of this event both in shallow water sediments and in the Mediterranean. The carbon isotope excursion precedes an oxygen isotope excursion which also was recognized in deep-sea records. Major episodes of phosphogenesis and platform drowning preceded the carbon isotope excursion by up to millions of years

All-aromatic biphenylene end-capped polyquinoline and polyimide matrix resins

Biphenylene end-capped polyquinoline and polyimide resins afford low void content graphite-reinforced composites with good initial properties. However, with both resins, rapid degradation occurs during oxidative isothermal aging at elevated temperatures. The degradation is not observed during isothermal aging under a nitrogen atmosphere which suggests that the biphenylene end-cap (or the resulting crosslink/chain extension structures) is not particularly thermooxidatively stable. The nature of the thermooxidative instability is currently under investigation

Meaningful Instruction of Basic Multiplication Facts: Applying Constructivist Concepts to Basic Fact Acquisition

In the United States, third grade students are expected to be fluent in the 100 basic math multiplication facts by the end of the school year. This action research project investigated the correlation between the use of constructivist principles for learning the 100 basic math multiplication facts and its impact on student understanding of mathematical reasoning concepts. The study involved twenty-two students in a midwest suburban third grade Christian school classroom for a 30-day period. An average of one hour a day was spent in math class with varied use of individual, partner, small group and large group work and instruction throughout the weeks. In the study basic multiplication facts were introduced through the use of strategies that included exploration, manipulative objects, guided reinvention, developmental pacing, interactive dialogue and relational understanding with the goal of building fluency in the facts and also impact understanding in other areas of math reasoning. The pretest and posttest were the Fall and Winter MAP Math tests respectively. The results of the study indicated a positive impact in overall math scores for students who scored at or below 80th percentile on the Fall MAP math test and a positive impact for males in overall algebraic reasoning

Der niederländische Weg : durch Konsens zum Erfolg (The Dutch way: success through consensus)

"In the 1980s the Netherlands found itself in a more far-reaching crisis than its European neighbours. The essential features of the policy reorientation - essentially wage restraint and reduction of working time, together with the linking of the Dutch Guilder to the D-Mark - have been retained ever since but have been gradually supplemented with stages of reform in the employment and social systems. In the meantime market regulation, privatisation, decentralisation and the linking of the various systems and the public administrations as well as the policy objective of reducing the rate of inactivity and thus of stemming corresponding benefits have come to the fore. This process of constantly and pragmatically modernising the employment and social security systems has been made possible not least by consultation and by the remarkable continuity of decisions taken by all those concerned. In explanation some institutional particularities of the employment system (wage determination process, statutory minimum wage, dismissal protection, flexible employment relationships, labour market policy) and of the social security system (benefits for unemployment, retirement, invalidity, sickness and need) are illustrated. On the whole it has been possible in the Netherlands to improve competitiveness and the employment results as well as to modernise the employment and social security system without giving up the principle of a common basic protection against the large social risks. In section 4 some factors of an economic explanation for the Dutch employment success are discussed; this covers wages, including non-wage labour costs, labour productivity taking into account the reduction in working hours, and macroeconomic growth. In the final section some considerations are made as to what stimulus the Netherlands provide with its set of macroeconomic and structural reform stages over a period of 11/2 decades and which of them could be of particular interest for the Federal Republic of Germany." (Author's abstract, IAB-Doku) ((en))Arbeitslosigkeitsbekämpfung, Beschäftigungspolitik, Teilzeitarbeit - Förderung, Arbeitszeitverkürzung, Lohnpolitik, soziales System, Niederlande