Simultaneous Determination of Major,Minor, and Trace Elements in Agricultural and Biological Samples by Inductively Coupled Argon Plasma Spectrometry

Three techniques for biological and agricultural sample preparation are compared. Commercially available inductively coupled argon plasma (ICAP) direct-reading spectrometers have been used to determine 29 major, minor, and trace elements in biological or agricultural samples following a nitric-perchloric acid digestion. At levels below the detection limit of the instrument, 21 other elements were found. The hydride generation-ICAP technique was employed for the determination of As, Bi, Sb, and Se in the same sample types.     

Micelles in mixtures of sodium dodecyl sulfate and a bolaform surfactant

Mixtures composed of water, sodium dodecyl sulfate (SDS), and a bolaform surfactant with two aza-crown ethers as polar headgroups (termed Bola C-16) were investigated by modulating the mole ratios between the components. The two surfactants have ionic and nonionic, but ionizable, headgroups, respectively. The ionization is due to the complexation of alkali ions by the aza-crown ether unit(s). Structural, thermodynamic, and transport properties of the above mixtures were investigated. Results from surface tension, translational self-diffusion, and small angle neutron scattering (SANS) are reported and discussed. Interactions between the two surfactants to form mixed micelles result in a combination of electrostatic and hydrophobic contributions. These effects are reflected in the size and shape of the aggregates as well as in transport properties. The translational diffusion of the components in mixed micelles, in particular, depends on the Bola C-16/SDS mole ratio. Nonideality of mixing of the two components was inferred from the dependence of the critical micelle concentration, cmc, on the mole fraction of Bola C-16. This behavior is also reflected in surface adsorption and in the area per polar headgroup at the air-water interface. SANS data analysis for the pure components gives results in good agreement with previous findings. An analysis of data relative to mixed systems allows us to compute some structural parameters of the mixed aggregates. The dependence of aggregation numbers, nu(T), on the Bola C-16/SDS mole ratio displays a maximum that depends on the overall surfactant content and is rationalized in terms of the nonideality of mixing. Aggregates grow perpendicularly to the major rotation axis, as formerly observed in the Bola C-16 system, and become progressively ellipsoidal in shape.     

CP MAS 13C spectral editing and relative quantitation of a soil sample

A hydrofluoric acid (HF)-treated soil sample was studied by 13C NMR spectroscopy. Cross polarization (CP) Magic Angle Spinning (MAS) 13C spectral editing and relative CP peak quantitation, obtained through variable-contact-time experiments, were used to aid the interpretation of the spectrum. The combination of these two types of experiment allowed to obtain a higher degree of detail on the composition of the sample with respect to a standard CP MAS experiment.     

Determination of carbofuran in water by homogeneous immunoassay using selectively conjugate mastoparan and terbium/dipicolinic acid fluorescent complex

Homogeneous immunoassay (LITRFIA) for carbofuran (CF) determination was performed using liposomes and mastoparan (Mast) conjugate as cytolitic agent. Mast was conjugated to the 5-(2-2-dimethyl-2,3-dihydro-benzofuran-7-yloxy)-pentanoic acid (CPCF) both randomly and selectively to a single (V¹- or K⁴-) amino-group. The conjugated compounds have been tested for the cytolytic activity on liposomes trapping Tb/citrate complex. Dipicolinic acid (DPA) was used as fluorescent chelating agent. The CPCF–V¹–Mast derivative (retaining almost the same lytic activity as Mast) was used in the immunoassay in competition with standard CF. Liposome lysis was proportional to the standard concentrations in a dynamic range between 10 pg and 10 ng. Assay has been performed for tap water analysis and for 10 real samples taken from an agricultural area to the south of Milan. Recovery in samples spiked with two different CF concentrations was between 92.5 and 105%.     

Structure factors in granular experiments with homogeneous fluidization

Velocity and density structure factors are measured over a hydrodynamic range of scales in a horizontal quasi-2D fluidized granular experiment, with packing fractions φ ∈ [10%, 40%]. The fluidization is realized by vertically vibrating a rough plate, on top of which particles perform a Brownian-like horizontal motion in addition to inelastic collisions. On one hand, the density structure factor is equal to that of elastic hard spheres, except in the limit of large length-scales, as it occurs in the presence of an effective interaction. On the other hand, the velocity field shows a more complex structure which is a genuine expression of a non-equilibrium steady state and which can be compared to a recent fluctuating hydrodynamic theory with non-equilibrium noise. The temporal decay of velocity modes autocorrelations is compatible with linear hydrodynamic equations with rates dictated by viscous momentum diffusion, corrected by a typical interaction time with the thermostat. Equal-time velocity structure factors display a peculiar shape with a plateau at large length-scales and another one at small scales, marking two different temperatures: the "bath" temperature T(b), depending on shaking parameters, and the "granular" temperature T(g) < T(b), which is affected by collisions. The two ranges of scales are separated by a correlation length which grows with φ, after proper rescaling with the mean free path.     

Bounds on the crossing resolution of complete geometric graphs

The crossing resolution of a geometric graph is the minimum crossing angle at which any two edges cross each other. In this paper, we present upper and lower bounds to the crossing resolution of the complete geometric graphs.     

A Fast and Efficient Ultrasound-Assisted Extraction of Tocopherols in Cow Milk Followed by HPLC Determination

A fast HPLC method with fluorescence detector (FD) was developed for the determination of three tocopherols (TOCs) in milk samples from Modicana cattle breed. The ultrasound-assisted procedure was optimized for the extraction of TOCs prior to HPLC/FD analysis, reducing sample preparation time and allowing a fast quantification of α-tocopherol, δ-tocopherol and γ tocopherol. The optimized ultrasonic extraction combines an efficient and simple saponification at room temperature and a rapid HPLC quantification of TOCs in milk. The precision of the full analytical procedure was satisfactory and the recoveries at three spiked levels were between 95.3% and 87.8%. The linear correlations were evaluated (R² > 0.99) and the relative standard deviation (RSD) values for intra-day and inter-day tests at three spiked levels were below 1% for the retention time and below 5.20% for the area at low level spiking. The proposed procedure, reducing the experimental complexity, allowed accurate extraction and detection of three TOCs in milk samples from Modicana cattle breed.     

Spooky action-at-a-distance in general probabilistic theories

We call a probabilistic theory “complete” if it cannot be further refined by no-signaling hidden-variable models, and name a theory “spooky” if every equivalent hidden-variable model violates Shimony?s Outcome Independence. We prove that a complete theory is spooky if and only if it admits a pure steering state in the sense of Schrödinger. Finally we show that steering of complementary states leads to a Schrödinger?s-cat-like paradox.     

Quantum computation with programmable connections between gates

A new model of quantum computation is considered, in which the connections between gates are programmed by the state of a quantum register. This new model of computation is shown to be more powerful than the usual quantum computation, e.g. in achieving the programmability of permutations of N different unitary channels with 1 use instead of N uses per channel. For this task, a new elemental resource is needed, the quantum switch, which can be programmed to switch the order of two channels with a single use of each one.     

Iron speciation in ancient Attic pottery pigments: a non‐destructive SR‐XAS investigation

The present work reports a detailed investigation on the speciation of iron in the pigments of decorated pottery fragments of cultural heritage relevance. The fragments come from the Gioiosa Guardia archaeological site in the area of the `Strait of Messina' (Sicily, Southern Italy), and date back to VI–V century BC. The purpose of this study is to characterize the main pigmenting agents responsible for the dark‐red coloration of the specimens using non‐destructive analytical techniques such as synchrotron radiation X‐ray absorption spectroscopy (SR‐XAS), a well established technique for cultural heritage and environmental subjects. Absorption spectra were collected at the Fe K‐edge on the Italian beamline for absorption and diffraction (BM8‐GILDA) at the European Synchrotron Radiation Facility in Grenoble (France). In order to determine the speciation of Fe in the samples, principal component analysis and least‐squares fitting procedures were applied to the near‐edge part of the absorption spectra (XANES). Details on the local structure around the Fe sites were obtained by analyzing the extended part of the spectra (EXAFS). Furthermore, an accurate determination of the average Fe oxidation state was carried out through analysis of the pre‐edge peaks of the absorption spectra. Samples resulted composed of an admixture of Fe₂O₃ (hematite or maghemite) and magnetite (Fe₃O₄), occurring in different relative abundance in the dark‐ and light‐colored areas of the specimens. The results obtained are complementary to information previously obtained by means of instrumental neutron activation analysis, Fourier transform infrared absorbance and time‐of‐flight neutron diffraction.