Eucalyptus nitens: nanomechanical properties of bark and wood fibers

In this study, Eucalyptus nitens species was nano-characterized to determine variability in nanomechanical properties within the cellular ultra-structure between the bark and wood fibers. Three factors, including site (2 levels), family (2 levels) and fiber type (bark and wood) were analyzed using three response variables, including the elastic modulus (E), hardness (H) and ductility ratio (E/H) in the middle lamella (ML) and the cell wall within the S2 layer. The results indicated significant differences for E _S2 and H _S2 when comparing fiber types: E _S2≈12.52 GPa and H _S2≈0.31 GPa for wood fiber and E _S2≈10.81 GPa and H _S2≈0.26 GPa for bark fiber. There is not statistically significant difference in ductility ratio (E/H) in S2 and ML between fiber types. These results indicate that bark and wood fibers can be used together or separately in the development of new composite materials and engineering products.     

Multianalytical Study of Patina Formed on Archaeological Metal Objects from Bliesbruck-Reinheim

 Patinas naturally formed on archaeological bronze alloys were characterized using light microscopy (LM), micro energy dispersive X-ray fluorescence analysis (μ-EDXRF), time of flight secondary ion mass spectrometry (TOF-SIMS) and scanning electron microscopy in combination with energy dispersive X-ray microanalysis (SEM/EDX). The examinations carried out on cross-sections of samples have shown that in all samples the copper content in the corrosion layer is lower than in the bulk, while an increase of tin and lead could be observed. Two different types of corrosion were found: first type, a corrosion formation leading to a three layer structure was observed on lead bronze. The outer layer consists mainly of Cu(II) compounds and soil material, followed by a fragmented layer of cuprous oxide and the surface layer of the alloy, where a depletion of copper and an enrichment of tin and high amounts of Cl could be detected. The second type of corrosion is characterized by a two layer structure on the tin bronze sample consisting of an outer layer with copper containing corrosion products and a layer with cracks, which reveals a depletion of copper whereas tin and lead are enriched. Also high amounts of Si were detected in this surface layer.     

Methane Conversion Over Sr2+/La2O3 Catalyst Modified with Nickel and Copper

Methane transformation over Ni and Cu modified Sr²⁺/La₂O₃ catalysts has been studied. These species favor formation of reducible mixed oxides and change the surface reactivity of the Sr²⁺/La₂O₃ system, modifying the reaction mechanism, since Sr²⁺/La₂O₃ favors methane oxidative coupling but with copper methane combustion is favored and nickel favors partial oxidation.     

Hochschild Cohomology and the Coradical Filtration of Pointed Coalgebras: Applications

In this paper we show that there is a close connection between the coradical filtration of a pointed coalgebra and the Hochschild cohomology of that coalgebra with coefficients in some one-dimensional bicomodules. As an application, for a given prime numberpand an algebraically closed fieldkof characteristic 0, we classify all pointed Hopf algebras of dimensionp³overk.     

Multi-element speciation of metalloproteins in fish tissue using size-exclusion chromatography coupled "on-line" with ICP-isotope dilution-time-of-flight-mass spectrometry

An on-line isotope dilution (ID) method in combination with the coupling of size-exclusion high-performance liquid chromatography (SE-HPLC) to an axial inductively coupled plasma time-of-flight mass spectrometer (ICP-TOFMS) was applied to the quantitative speciation of Cu, Zn and Cd in carp and eel cytosols. Quantitative information on the distribution of essential and toxic metals between the different molecular weight fractions in kidney cytosols of control and Cd exposed carp was obtained with species-unspecific spiking by post-column addition of the enriched isotopes 65Cu, 67Zn and 106Cd. The isotope ratios 63Cu/65Cu, 64Zn/67Zn and 114Cd/106Cd, were monitored by ICP-TOFMS in transient signal mode. The determination of the total cytosolic element concentration was performed by flow injection conventional nebulization ICP-TOFMS. Speciation differences were encountered between control and Cd-stressed carp, indicating that quantitative speciation studies might be useful for ecotoxicological and biomonitoring purposes. Application of this methodology to quantitation of metals associated with metallothioneins (MT) in European eel, sampled at three different sites in Flanders, Belgium was also addressed. A significant increase of the amount of Cd, Cu and Zn bound to hepatic MT was observed with the increase of the total metal and MT concentrations of hepatic eel tissue.     

Static secondary ion mass spectrometry for organic and inorganic molecular analysis in solids

The use of mass spectra in secondary ion mass spectrometry (S-SIMS) to characterise the molecular composition of inorganic and organic analytes at the surface of solid samples is investigated. Methodological aspects such as mass resolution, mass accuracy, precision and accuracy of isotope abundance measurements, influence of electron flooding and sample morphology are addressed to assess the possibilities and limitations that the methodology can offer to support the structural assignment of the detected ions. The in-sample and between-sample reproducibility of relative peak intensities under optimised conditions is within 10%, but experimental conditions and local hydration, oxidation or contamination can drastically affect the mass spectra. As a result, the use of fingerprinting for identification becomes compromised. Therefore, the preferred way of interpretation becomes the deductive structural approach, based on the use of the empirical desorption–ionisation model. This approach is shown to allow the molecular composition of inorganic and organic components at the surface of solids to be characterised. Examples of inorganic speciation and identification of organic additives with unknown composition in inorganic salt mixtures are given. The methodology is discussed in terms of foreseen developments with respect to the use of polyatomic primary ions.     

Comparative study of crude oils from the Machete area in the Eastern Venezuelan Basin by pyrolysis of asphaltenes

This work is an analysis of crude oil samples from the two most recent producing wells in the Machete area (Orinoco Tar Belt, Venezuela). The aim is to determine the type of environment in which the precursor organic materials were deposited. In spite of the fact that the degree of maturity and the biodegradation of the two crude oils are similar, their characterization leads us to conclude that they have very distinctive and different origins. The comparative study was performed by separating their main fractions, pyrolysis of asphaltenes, and further identification of several indicators (aromatic, polar and sulfur compounds, linear aliphatic hydrocarbons, and cadalene). Moreover, several biomarkers (terpanes, hopanoids and steranes) present in the saturated fractions obtained from the two crude oils were analyzed by using gas chromatography combined with mass spectrometry (GC–MS). The statistical study of geochemical indicator values and relative proportions of lipid and lipid-like biomarkers present in products from asphaltene pyrolysis shows a high probability of there being two distinct crude oil families from the Machete area.     

Mass spectrometric study of the dissolution behaviour of sanidine

Secondary ion mass spectrometry has been used to measure the silicon isotope ratio as a function of depth in feldspars after their interaction with dilute acid solutions. The reaction of feldspars with aqueous solutions implies the formation of relatively thick K, Na and Al depleted surface layers, especially when the dissolution experiments are conducted in the presence of silica powder. The latter is used to lower the silicon concentration gradient at the solid-solution interface. This generates an uncertainty in the interpretation of the results: the depleted surface layer may have been formed by leaching of the above-mentioned elements from the solid, or by precipitation of silica from the solution. Measurements using isotopically enriched silica powder (³⁰SiO₂) were therefore performed in the hope that they would solve the uncertainty. The measured silicon isotope ratio at the surface of the mineral appears to be different from its normal terrestrial value and from the enriched powder value, having a value somewhere in between which decreases towards its normal value as a function of depth. In addition the silicon isotope ratio of the solution, which was measured using thermal ionization mass spectrometry, shows an altered value compared with the enriched silica powder. The results of both analyses therefore indicate an exchange in silicon between solid and solution and suggest the combination of two or more mechanisms during dissolution.     

Density of O-atoms in an Afterglow Reactor During Treatment of Wool

Density of neutral oxygen atoms in the ground state has been measured during treatment of wool fabric samples. Samples were placed in an afterglow reactor with a volume of about 5 l, which was pumped with a two stage rotary pump with the nominal pumping speed of 28 m³/h. The source of the oxygen atoms was a microwave discharge operating in the surfatron mode at 2.45 GHz and adjustable output power up to 300 W. The density of O-atoms in the afterglow chamber was measured with a fiber-optics catalytic probe. For the empty reactor, the O density depended on discharge parameters and was between 0.8 and 2.8 × 10²¹ m⁻³ at 40 and 50 Pa respectively. During the treatment of wool, the O density depended largely on the exposure time. For untreated samples, the O density was below the detection limit of the probe, while prolonged treatment allowed for recovering the O density. The recovery always occurred after having submitted wool samples to the dose of the order of 10²³ atoms/m². The results were explained by oxidation of the thin lipid layer on the surface of the wool fibres.