The effects of eluent mixing on TLS detection in gradient elution HPLC

The effects of changing solvent composition on the LOD of TLS detection in gradient elution HPLC have been studied from the perspective of thermo-optical properties of the solvent. Hyphenated gradient high-performance liquid chromatography (HPLC)-thermal lens spectrometry (TLS), was used to separate and detect 13 carotenoid compounds and two chlorophylls. Utilization of mixing coils into the system reduces the inhomogeneities during eluent changes and therefore enables the application of thermal lens detection in the gradient HPLC method. For gradient chromatographic conditions in which the thermo-optical properties and related enhancement factor change as much as 50% over 10 min, the LODs for the TLS detector were enhanced by as much as three times in comparison with UV-Vis detection. For the isocratic part of the chromatogram, up to a tenfold improvement of LODs was achieved with TLS detection.     

A methodological study of mercury speciation using dogfish liver CRM (DOLT-2)

The purpose of the study was to optimise analytical methods for determination of the chemical speciation of mercury in studies of protective mechanisms of selenium. Optimisation of the methods was performed using CRM DOLT-2 (Dogfish liver), both in its original form and after separation of various fractions. The sample was homogenised with 10 mM Tris-HCl buffer (pH 7.6) and ultracentrifuged. The soluble phase obtained was applied to a size exclusion chromatography column (Sephadex G-75 column) for separation of various protein fractions. Total mercury (total Hg), monomethyl mercury (MeHg) and selenium (Se) were determined in whole dogfish liver tissue and its soluble and insoluble phases (pellet). Different approaches for determination of total Hg and MeHg were compared. Simultaneous determination of MeHg and inorganic mercury (Hg2+) was based on alkaline dissolution and/or acid leaching, followed by ethylation, room temperature precollection, isothermal gas chromatography (GC), pyrolysis and detection with cold vapour atomic fluorescence spectrometry (CVAFS). The sum of MeHg and Hg2+ was compared to total Hg results obtained by acid digestion and CVAAS detection. The accuracy of MeHg determination was checked by its determination using acid leaching at room temperature, solvent extraction, back extraction into Milli-Q water, ethylation, GC and CVAFS detection. For the insoluble phase it is recommended to use solvent extraction for MeHg and acid digestion CVAAS for total Hg. For determination of MeHg and Hg2+ in the lyophilised sample and water soluble fractions containing low concentrations of mercury species, the simultaneous measurement of MeHg and Hg2+ after alkaline dissolution is the most appropriate method.     

Tritium in organic matter around Krško Nuclear Power Plant

The aim of the research was to obtain first results of tritium in the organic matter of environmental samples in the vicinity of Kr?ko NPP. The emphasis was on the layout of suitable sampling network of crops and fruits in nearby agricultural area. Method for determination of tritium in organic matter in the form of Tissue Free Water Tritium (TFWT) and Organically Bound Tritium (OBT) has been implemented. Capabilities of the methods were tested on real environmental samples and its findings were compared to modeled activities of tritium from atmospheric releases and literature based results of TFWT and OBT.     

Removal of nickel(II) ions from aqueous solutions using the natural clinoptilolite and preparation of nano-NiO on the exhausted clinoptilolite

The natural zeolite tuff (clinoptilolite) from a Serbian deposit has been studied as adsorbent for Ni(II) ions from aqueous solutions. Its sorption capacity at 298 K varies from 1.9 mg Ni g⁻¹ (for the initial solution concentration of 100 mg Ni dm⁻³) to 3.8 mg Ni g⁻¹ (for C₀ = 600 mg Ni dm⁻³) and it increases 3 times at 338 K. The sorption is best described by the Sips isotherm model. The sorption kinetics follows the pseudo-second-order model, the activation energies being 7.44, 5.86, 6.62 and 6.63 kJ mol⁻¹ for C₀ = 100, 200, 300 and 400 mg Ni dm⁻³, respectively. The sorption involves a film diffusion, an intra-particle diffusion, and a chemical cation-exchange between the Na⁺ ions of clinoptilolite and the Ni²⁺ ions. The sorption is endothermic (ΔH° being 37.9, 33.4, 30.0, 27.7 and 24.3 kJ mol⁻¹ for C₀ = 100, 200, 300, 400 and 600 mg Ni dm⁻³, respectively) and spontaneous in the 298-338 K temperature range. Thermal treatment of the Ni(II)-loaded clinoptilolite results in the formation of spherical nano-NiO particles of approx. 5 nm in diameter which are randomly dispersed in the clinoptilolite lattice.     

Rawls’s Rejection of Preinstitutional Desert

For many, the idea that people should be rewarded in proportion to what they deserve is the very essence of distributive justice. However, while the notion of moral desert is otherwise widely accepted, Rawls rejects it entirely in his A Theory of Justice. Many authors have argued that Rawls’s claims about desert have serious and unappealing consequences for his conception of justice as fairness, and also that they deny the possibility of autonomous choice to the very agents whose decisions are supposed to underlie Rawls’s approach to justice. In this paper, I analyze the arguments of those who believe that Rawls can be interpreted in a way that doesn’t in fact deny either desert or the possibility of autonomous action. I conclude by allowing for the interpretation that Rawls does not necessarily deny autonomous action, but I contend that he nevertheless finds the idea of preinstitutional desert entirely off the mark.     

An algorithm for computing minimal curves

Let ?³ be the 3-dimensional projective space over an algebraically closed field K of characteristic 0, and R be the graded polynomial ring K[x ₀,x ₁,x ₂,x ₃]. If C is a curve of ?³, let M _c := ⊕ H ^l I _C (n) be its Hartshorne-Rao module: it is a graded R-module of finite length which, up to a shift in degrees, characterizes the biliaison class of C. M. Martin-Deschamps &; D. Perrin (Sur la classification des courbes gauches. Astérisque 184–185 (1990)) have proved that in every biliaison class of non arithmetically Cohen-Macaulay curves there exists a minimal curve, unique up to a deformation with constant cohomology and Hartshorne-Rao module, that is a curve C such that, if C ₁ is any curve in the biliaison class of C, then M _{C 1} = M _c(?n), with n ≧ 0. They have moreover given an algorithm for the computation of a minimal curve, based on the computation and the analysis of the minors of given orders of some submatrices of the second syzygy matrix σ ₂ of M. The aim of this paper is to give an improvement to the algorithm for computing a minimal curve of a given Hartshorne-Rao module. The key remark is that the information obtained from σ ₂ can analogously be obtained from the matrix f(σ ₂) with entries in the polynomial ring K[u], where f:R → K[u] is a map which evaluates the variables of R to random linear polynomials in K[u]. The advantage of this approach is first, that the computations are done in a simpler polynomial ring and second, that in K[u]|we can take advantage of the Smith Normal Form algorithm to analyze the structure of the minors of the given matrices. The algorithm is therefore probabilistic but rather efficient and allows to compute (the invariants of) a minimal curve associated to modules whose syzygies matrices are considerably large. The algorithms presented here have been partially implemented and tested in the computer algebra systems CoCoA, Maple and Macaulay.     

Mesoporous aluminophosphate thin films with cubic pore arrangement

Mesoporous aluminophosphate thin films with 3D cubic (Im3m) pore arrangement were synthesized for the first time. Thin films were templated with block copolymer nonionic templates Pluronic F127 and F108 and deposited on a glass substrate by dip-coating. In situ SAXS investigations show the formation of a highly ordered mesostructure upon the dip-coating process, which remains stable up to at least 670 K. A cubic mesostructure was observed also by TEM. Template removal process was monitored by TG and FT-IR. A transition from an amorphous aluminophosphate gel to a well-defined aluminophosphate framework was observed by MAS NMR.     

Green Solvents as an Alternative to DMF in ZIF-90 Synthesis

The use of green solvents as an alternative to dimethylformamide (DMF) in the synthesis of zeolitic imidazolate framework-90 (ZIF-90) was investigated. Two biobased aprotic dipolar solvents Cyrene^TM and γ-valerolactone (GVL) proved to successfully replace DMF in the synthesis at room temperature with a high product yield. While the Cyrene^TM—based product shows reduced porosity after activation, the use of GVL resulted in materials with preserved crystallinity and porosity after activation, without prior solvent exchange and a short treatment at 200 °C. The primary particles of 30 nm to 60 nm in all products further form agglomerates of different size and interparticle mesoporosity, depending on the type and molar ratios of solvents used.     

MnOx Nanoparticles Supported on a New Mesostructured Silicate with Textural Porosity

A two‐step synthesis of a novel mesostructured silicate, KIL‐2, and its manganese‐containing analogue, Mn/KIL‐2, has been developed. KIL‐2 possesses interparticle mesopores with pore dimensions between 5 and 60 nm and a surface area of 448 m². The mesopores are formed by the aggregation of silica nanoparticles, which creates a network with interparticle voids. The particle size and the pore diameters depend on the temperature of the ageing step (first step) and on the solvothermal treatment in ethanol (second step), respectively. Mn/KIL‐2 contains octahedrally coordinated Mn³⁺ (80 %) and tetrahedrally coordinated Mn²⁺ (20 %) ions. Mn³⁺ ions are present in the extra‐framework MnO_x nanoparticles with typical dimensions of 2 nm, which are homogeneously distributed throughout the material. Mn²⁺ ions occur as isolated manganese framework sites. The material is also able to retain its structure characteristics after the hydrothermal treatment in boiling water. Because of its non‐toxic nature and cost‐effective synthesis, Mn/KIL‐2 thus exhibits properties that are needed for an environment‐friendly catalyst.