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).     

Synthesis of N-benzyl-des-D-ring lamellarin K via an acyl-Claisen/Paal-Knorr approach

Lamellarin K is a complex pyrrole natural product and member of the lamellarin family – a group of natural products known for their potent biological activities, such as, antiproliferative activity and inhibition of P-gp mediated drug efflux pumps. We herein describe the synthesis of the N-benzyl-des-D ring analogue of lamellarin K using a route that centres on an acyl-Claisen reaction to eventually prepare a highly-functionalised 1-aryl-4-methyl-1,4-diketone. Paal-Knorr pyrrole formation using this diketone undergoes auto-oxidation to give a fully-substituted 5-formyl pyrrole which was converted into the natural lactone B ring. Antiproliferative testing of the N-benzyl-des-D ring analogue gave an IC₅₀ of 2.63 μM against the MDA-MB-231 breast cancer cell line.     

Preparation,catalytical activity and crystal structure of a heptanuclear zinc acetate cluster

Reaction of [Zn₄(µ₄-O)(O₂CCH₃)₆] with one equivalent of 4-tertiary-butylpyridine leads to a nearly quantitative formation of the heptanuclear cluster [Zn₇O₂(O₂CCH₃)₁₀(^tbupy)₂] (1). Here, we present the crystal structure of 1 and first results of the examination of its catalytic activity in transesterification reactions and polymerization of lactide compared to the activity of [Zn₄(µ₄-O)(O₂CCH₃)₆] in the presence of 4-tertiary-butylpyridine.     

The influence of π-π-stacking on the light-harvesting properties of perylene bisimide antennas that are covalently linked to a [60]fullerene

A flexible organic triad consisting of two perylene bisimide antennas covalently linked to a [60]fullerene by flexible spacers has been synthesized and studied by electrochemistry, steady-state and time-resolved spectroscopy. We found that π-π-stacking of the two antenna subunits has considerable impact on the photophysics of the system and leads to a reduction of the effective light-harvesting efficiency of the assembly. This finding is important for light harvesting in flexible materials based on the dye antenna-fullerene concept.     

Public understanding of science and the perception of nanotechnology: the roles of interest in science,methodological knowledge,epistemological beliefs,and beliefs about science

In this article, we report data from an online questionnaire study with 587 respondents, representative for the adult U.S. population in terms of age, gender, and level of education. The aim of this study was to assess how interest in science and knowledge as well as beliefs about science are associated with risk and benefit perceptions of nanotechnology. The findings suggest that the U.S. public is still rather unfamiliar with nanotechnology. Those who have some knowledge mainly have gotten it from TV and the Internet. The content of current media reports is perceived as fairly positive. Knowledge of scientific methods is unrelated to benefit and risk perceptions, at least when other predictors are controlled. In contrast, positive beliefs about science (e.g., its impact on economy or health) and more sophisticated epistemological beliefs about the nature of scientific knowledge are moderately linked to more positive perceptions of nanotechnology. The only exception is the perception of scientific uncertainty: This is associated with less positive evaluations. Finally, higher engagement with science is associated with higher risk perceptions. These findings show that laypersons who are engaged with science and who are aware of the inherent uncertainty of scientific evidence might perceive nanotechnology in a somewhat more differentiated way, contrary to how it is portrayed in the media today.     

Radon measure-valued solutions of nonlinear strongly degenerate parabolic equations

We prove the existence of suitably defined weak Radon measure-valued solutions of the homogeneous Dirichlet initial-boundary value problem for a class of strongly degenerate quasilinear parabolic equations. We also prove that: \((i)\) the concentrated part of the solution with respect to the Newtonian capacity is constant; \((ii)\) the total variation of the singular part of the solution (with respect to the Lebesgue measure) is nonincreasing in time. Conditions under which Radon measure-valued solutions of problem \((P)\) are in fact function-valued (depending both on the initial data and on the strength of degeneracy) are also given.     

Effect of the his residue on the cyclization of b ions

The MSⁿ spectra of the [M + H]⁺ and b ₅ peaks derived from the peptides HAAAAA, AHAAAA, AAHAAA, AAAHAA, and AAAAHA have been measured, as have the spectra of the b ₄ ions derived from the first four peptides. The MS² spectra of the [M + H]⁺ ions show a substantial series of b_n ions with enhanced cleavage at the amide bond C-terminal to His and substantial cleavage at the amide bond N-terminal to His (when there are at least two residues N-terminal to the His residue). There is compelling experimental and theoretical evidence for formation of nondirect sequence ions via cyclization/reopening chemistry in the CID spectra of the b tons when the His residue is near the C-terminus. The experimental evidence is less clear for ions when the His residue is near the N-terminus, although this may be due to the use of multiple alanine residues in the peptide making identifying scrambled peaks more difficult. The product ion mass spectra of the b ₄ and b ₅ ions from these isomeric peptides with cyclically permuted amino acid sequences are similar, but also show clear differences. This indicates less active cyclization/reopening followed by fragmentation of common structures for b _n ions containing His than for sequences of solely aliphatic residues. Despite more energetically favorable cyclization barriers for the b ₅ structures, the b ₄ ions experimental data show more clear evidence of cyclization and sequence scrambling before fragmentation. For both b ₄ and b ₅ the energetically most favored structure is a macrocyclic isomer protonated at the His side chain.     

Influence on elemental status by hip-endoprostheses

For many clinical purposes various artificial devices are applied, which contact human tissue and can thus cause adverse reactions between prosthetic surfaces and body components. Of the many materials applied for orthopaedic joint replacements the most common are cobalt-chromium-molybdenum alloys. In these cases considerable amounts of cobalt-chromium-molybdenum wear particles are released from the prostheses which have to be regarded as a cause of long-time problems for the patient.Since these particles are dissolved in body fluids of the surrounding area they are distributed in the whole body via blood. Elevated metal concentrations have been found in blood and urine of persons with endoprostheses. Partly the metals are excreted via urine, but to some extend they accumulate in different organs.Therefore this study dealt with the development of an analytical method for the determination of seven relevant trace elements, namely Al, Co, Cr, Mo, Nb, Ni, and Ti in nine kinds of human tissue (brain, heart, kidney, liver, lung, muscle, lymphatic nodes, spleen, body fat) starting with drawing of the sample, sample work up and finally analysis by means of atomic spectrometry. The optimized method was then applied to determine the metal contents in organs of persons (post mortem) with total hip replacements with metal on metal bearing surfaces. Comparison of the data obtained with those of persons without hip-endoprostheses shows that brain and lung are the main targets for elemental accumulation in persons with hip-endoprostheses. Mo and Nb represent the elements with the highest tendency to be accumulated.