A study of the exposure of various population groups to platinum in Vienna (Austria) through urine analysis by inductively coupled plasma-mass spectrometry

Platinum is emitted to environment by automobile catalytic converters (ACCs), hospitals, noble metal refineries, and other industries. Due to abrasion of ACCs platinum leaves the cars with the exhaust fumes and can thus be found in urban and rural atmospheres. To study the exposure to this element its concentration in urine is determined. Urine represents an often used specimen for monitoring studies, as it plays an important role in the elimination of various substances from the body and in addition it can be collected easily. It is supposed that the Pt-intake depends on the physical activity of a person, i.e. the amount of air inhaled and food consumed. Therefore subjects without and with one or two hip-endoprostheses were selected for this monitoring study. The medians obtained for the Pt-concentration of the urine-samples of these three groups were 3.7 µg/g, 3.3 µg/g and 1.9 µg/g for persons with no, one and two prostheses, respectively. Applying a Mann-Whitney-U-test on these data leads to a p-value of 0.051 comparing the groups with n = 0 and n = 2, and a p-value of 0.052 for n = 1 and n = 2 (n = number of prostheses).     

Water revealed as molecular mirror when measuring low concentrations of sugar with near infrared light

Near infrared spectroscopy is an overtone spectroscopy regarded as a quick and non-destructive method that provides analytical solutions for components that represent approximately 1% or more of the total mass of the investigated composite samples. Aquaphotomics offers the possibility for disentanglement of information remaining hidden in the spectra when conventional data evaluation methods are used, since this concept utilizes changes of the water structure induced by the measured solute as specific molecular vibrations at water bands. Here, near infrared technique and aquaphotomics are applied for non-destructive identification and quantification of mono- and di-saccharide solutes at 100–0.02 mM concentration that is accepted as unachievable with near infrared spectroscopy. The results presented in this study support the aquaphotomics' water molecular mirror concept that explores spectral changes related to water molecular rearrangements caused by minute changes of the solutes in the aqueous systems. The method provides quick and accurate alternative for classical analytical measurements of saccharides even at millimolar concentration levels.     

The geometry of the nitroguanyl fragment in the simplest nitroguanidine derivatives in the absence of intermolecular interactions: The gas electron diffraction data on 1,1,3,3-tetramethyl-2-nitroguanidine

The structures and force fields of the equilibrium forms of 2-nitroguanidine (1), 1,1,3,3-tetramethyl-2-nitroguanidine (2), and nitroguanyl azide (3) were determined in the MP2(full)/6-311G(3df, 2p) approximation; wagging-inversion motions of the N amine atoms were studied. The internal rotation potential function of the NO₂ group was calculated for 1. Similar functions for 1 and 2 were also obtained in the MP2(full)/6-311G(d, p) approximation. Direct one-dimensional problems for a nonrigid model were solved by the variational method, and the distribution of torsional levels was obtained. In the region of potential minimum, rotation in both molecules had the character of large-amplitude motions. For the first time, electron diffractions data were obtained at 100°C for molecule 2 without noticeable traces of substance decomposition. A structural r _e analysis was performed using the model of large-amplitude motions for characteristic NO₂ group torsional vibrations. Vibrational corrections to internuclear distances and mean amplitudes were calculated taking into account nonlinear kinematic effects using the force fields obtained in this work. The geometry of molecule 2 calculated in the MP2(full)/6-311G(3df, 2p) approximation well corresponds to the gas electron diffraction data. The parameters of molecule 2 in the crystalline phase, however, differ substantially from the parameters of the free molecule. This corresponds with the suggestion of the influence of intermolecular H-bonds involving the imine nitrogen atom and nitro groups oxygen atoms.     

Basic modes of three-dimensional polymer crystal associations: Interlocked single crystals and crystal halves

Tridimensional associations of lamellar polymer single crystals, grown from dilute solutions, are described as derived from their sedimentation patterns. These associations include interlocked crystals and decorating crystal halves. The origin of these crystals and their mutual orientation are discussed and tentatively interpreted by specific interactions between the fold surface and the crystallizing chains.     

Dérivés C-glycosyliques. VII. Synthèse et réactions de nitrones dérivées de sucres. Communication préliminaire

The syntheses of three types of sugar nitrones (aldonitrone, ketonitrone and α-β unsaturated aldonitrone) are described. On 1,3-dipolar cycloaddition with phenylacetylene, the aldonitrone gave two Δ₄-isoxazolines epimeric at the new asymetric carbon, while the same reaction on the ketonitrone led to a spiro-Δ₄-isoxazoline. The reaction of these nitrones with carbon nucleophiles like phenylethynylmagnesium bromide constitutes a novel chain-extension reaction in carbohydrate chemistry.     

Efficient multipole expansion: Choice of order and density partitioning techniques

Two approaches to improve the convergence of the multipole series were considered: 1) an increase in the order of the expansion; 2) decomposition of the molecular charge density into smaller distributions. New decompositions of the molecular electronic density and a computational procedure to generate high-order moments are presented. The accuracy and timing of test calculations on the H₂O ... H₂O system are given and suggestions are made for optimizing the choice of an expansion for more general systems.We express our appreciation to the National Institutes of Health which supported this work under Grant 1 R01 GM 20436-02.     

Isobaric thermal behavior of glasses during uniform cooling and heating: Dependence of the characteristic temperatures on the relative contributions of temperature and structure to the rate of recovery. II. A one-parameter model approach

Isobaric variations of the characteristic temperatures T_g and T_max, obtained on uniform cooling and heating of glasses, are investigated in terms of their dependence on the relevant experimental variables, using a single retardation time model. The corresponding partial derivatives of T_g and T_max are derived as functions of the partition parameter x (ranging between zero and unity), which determines the relative contributions of temperature and structure to the retardation time. It is shown that the variation of T_g with the cooling rate is independent of x. In contrast, T_max critically depends on x, and its value as well as those of its three partial derivatives are linear functions of x^?1. The variations of T_max are analyzed in terms of a set of reduced variables, leading to simple reduction rules between any two of the experimental variables when the third is kept invariant. The reduction rules are further substantiated by investigating the behavior of glasses in two-step thermal cycles, which result in a unique set of inter-relationships between any pair of the partial derivatives of T_max, whatever the value of x. The results are discussed in terms of their relevance to the behavior of real glasses.     

Complex behavior in the formaldehyde-sulfite reaction

The formaldehyde-sulfite reaction is an example of an "acid-to-alkali" clock. It displays an induction period, during which the pH varies only slowly in time, followed by a reaction event, during which the pH increases rapidly by several units. When the reaction is performed in a closed (batch) reactor, the clock time is found to increase with a decrease in initial concentrations of formaldehyde and sulfite and an increase in the total initial concentration of S(IV). At long times, following the clock event, there is a slow decrease in pH. In an open (flow) reactor, bistability between a low-pH steady state (pH approximately 6-8) and a high-pH steady state (pH approximately 11) is observed. Additionally, we report the existence of sustained, small-amplitude oscillations in pH in this system. An extended kinetic mechanism reproduces the batch behavior but fails to account for the complex behavior observed in the flow reactor. Possible additional reaction steps are discussed.