Determination of Trace Elements in Carbonaceous Samples by Graphite Furnace Atomic Absorption Spectrometry: Microwave Digestion Versus Slurry Sampling

 The determination of chromium, copper, manganese, nickel and vanadium in carbonaceous samples by slurry introduction graphite furnace atomic absorption spectrometry and after microwave assisted digestion are compared. Parameters such as atomization and pyrolysis temperatures, and surfactant concentration as well as the homogenization procedure were optimized. The slurries were prepared by mixing adequate amounts of the pulverized samples with 0.05% Triton X-100, sonicating for, at least, 40 seconds during the preparation to separate aggregates and for 20 seconds immediately before being autosampled. It was not necessary to use modifiers and calibration against aqueous standards was possible for all the elements. Coke, graphite and certified coal samples were analyzed, and no significant difference was observed using both procedures. Good agreement between found and certified values was obtained. Received January 24, 2000. Revision September 26, 2000.     

Quality Factor of Inhomogeneous Plane Waves

Acoustical Physics - We first compare two apparently dissimilar expressions for the quality factor Q of inhomogeneous plane waves in isotropic viscoelastic media, where Q is defined as the result...     

Chemometric characterization of gamma irradiated chestnuts from Turkey

Chestnut (Castanea sativa Miller) is a valuable natural resource, with high exportation levels. Due to their water content, chestnuts are susceptible to storage problems like dehydration or development of insects and microorganisms. Irradiation has been revealing interesting features to be considered as an alternative conservation technology, increasing food products shelf-life. Any conservation methodology should have a wide application range. Hence, and after evaluating Portuguese cultivars, the assessment of irradiation effects in foreign cultivars might act as an important indicator of the versatility of this technology. In this work, the effects of gamma irradiation (0.0, 0.5 and 3.0 kGy) on proximate composition, sugars, fatty acids (FA) and tocopherols composition of Turkish chestnuts stored at 4 °C for different periods (0, 15 and 30 days) were evaluated. Regarding proximate composition, the storage time (ST) had higher influence than the irradiation dose (ID), especially on fat, ash, carbohydrates and energetic value. Sucrose exhibited similar behavior in response to the assayed ST and ID. The prevalence of ST influence was also verified for FA, tocopherols and sucrose. Lauric, palmitoleic and linolenic acids were the only FA that underwent some differences with ID. Saturated, monounsaturated and polyunsaturated fatty acids levels were not affected either by storage or irradiation. α-Tocopherol was the only vitamer with significant differences among the assayed ST and ID. Overall, Turkish cultivars showed a compositional profile closely related with Portuguese cultivars, and seemed to confirm that gamma irradiation in the applied doses did not change chestnut chemical and nutritional composition.     

A Note on the Extrinsic Phase Space Path Integral Method for Quantization on Riemannian Manifold Particle Motions — An Application of the Nash Embedding Theorem

We use Nash embedding for Riemann smooth manifolds to propose a constrained phase space path integral for quantization of one particle motion in a Riemannian manifold.     

Spaceability in Banach and quasi-Banach sequence spaces

Let X be a Banach space. We prove that, for a large class of Banach or quasi-Banach spaces E of X-valued sequences, the sets E-?_q∈Γ?_q(X), where Γ is any subset of (0,∞], and E-c₀(X) contain closed infinite-dimensional subspaces of E (if non-empty, of course). This result is applied in several particular cases and it is also shown that the same technique can be used to improve a result on the existence of spaces formed by norm-attaining linear operators.     

Projections as averages of isometries on minimal norm ideals

In this paper, we consider projections on minimal norm ideals of B(H) that are represented as the average of two surjective isometries. We describe projections of the form

     

Photoelectrochemical sensor for determination of naringin at low oxidation potential using a modified FTO electrode with cadmium sulfide and titanium dioxide sensitized with chloroprotoporphyrin IX iron(III)

Journal of Solid State Electrochemistry - Naringin is a flavanone that has been studied due to its important properties, such as anti-inflammatory, anti-oxidant, anti-microbial, anti-viral,...     

Electronic structure and properties of camphorimine Cu(I) coordination polymers

The first Cu(I) coordination polymer with an aromatic‐substituted camphorimine ligand [(CuCl)(μ‐Cl) (Cu(H₂NC₆H₄NC₁₀H₁₄O)]_n was obtained from reaction of CuCl with 3‐(4‐aminophenylimino)‐1,7,7‐trimethylbicyclo[2.2.1]heptan‐2‐one (H₂NC₆H₄NC₁₀H₁₄O). The electronic and the surface properties (studied by X‐ray photoelectron spectroscopy) are consistent with two distinct coordination environments for the copper(I) atoms—tetrahedral and linear—for the polymer family [(CuCl)(μ‐Cl){Cu(YNC₁₀H₁₄O)}]_n. DFT band calculations reveal that the highest energy bands are more localized on the copper(I) tetrahedral sites than on the copper(I) linear sites. The redox properties of [(CuCl)(μ‐Cl){Cu(YNC₁₀H₁₄O)}]_n [Y = NMe₂ ( 2b ), NH₂, and H₂NC₆H₄NC₁₀H₁₄O ( 2a )] studied by cyclic voltammetry show that the oxidation potentials of the two copper centers are in fact indistinguishable. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012