Synthesis and Crystal Structure of a P-Hydridophosphoraniminato–Zirconium Complex and Reaction to the First Tris(hydrido)cyclotriphosphazene

The first oligomeric phosphazene in which each phosphorus center features a PH functionality ( 3 ) was obtained from the amidophosphane 1 or its zirconium complex 2 .     

Application of LC–TOF MS to analysis of hemoglobin acetaldehyde adducts in alcohol detoxification patients

Acetaldehyde adducts of hemoglobin have been regarded as potential biochemical markers of alcohol exposure. In this study a novel sensitive method using liquid chromatography coupled to time-of-flight mass spectrometry (LC–TOF MS) has been used to investigate changes in adduct levels in alcohol detoxification patients. Hemoglobin and authentic blood samples from 66 adults with an alcohol-dependence syndrome and from 12 children were analyzed for acetaldehyde modifications with and without trypsin digestion using LC–TOF MS. After in-vitro incubation of hemoglobin with increasing concentrations of acetaldehyde, followed by tryptic digestion, 21 modified peptide fragments could be identified from their accurate mass and retention time shift. Eight of these could also be detected in authentic human blood samples. Trace amounts in children’s blood were indicative of an endogenous source. Modified peptide levels in patients’ samples with and without ethanol were significantly different, as also were levels in samples from admission and from five days later. Samples obtained 5, 10, or 15 days after admission did not differ in adduct levels. The LC–TOF MS method was sensitive enough to detect acetaldehyde-modified hemoglobin peptides in blood samples from patients with an alcohol-dependence syndrome. However, elevated levels were only observed after recent ethanol consumption and decreased during five days of abstinence, suggesting that acetaldehyde-modified tryptic peptides of hemoglobin are potential biomarkers only for short-term ethanol ingestion.     

Endothelial f-actin depolymerization enables leukocyte transmigration

A demanding task of medicine is to understand and control the immune system. Central players in the cellular immune response are the leukocytes that leave the blood stream for host defense. Endothelial cells limit the emigration rate of leukocytes. Being located between blood and tissues, they permit or deny the passage. The exact mechanism of this process called diapedesis is not solved yet. Leukocytes can principally traverse either between cells (paracellularly) or directly through an individual endothelial cell (transcellularly). The transcellular way has recently gained experimental support, but it is not clear how the endothelial cytoskeleton manages to open and close a transmigratory channel. Atomic force microscopy was used to investigate the endothelial cytoskeleton. In order to directly access the leukocyte–endothelial interaction site, we applied a special protocol (“nanosurgery”). As a result, the endothelial cell turned out to become softer in a confined region strictly underneath the leukocyte. Fluorescence microscopy confirmed a depolymerization of the f-actin strands at the invasion site. Leukocytes dramatically rearrange the endothelial cytoskeleton to form transmigratory channels.     

Uranium determination in process chemicals: on the way to sub-pg/g concentrations

The detection limit of ICP-MS is affected by the sensitivity, the height of the blank and its relative stability i.e. precision, the accuracy and additionally by a bias or systematical error. The improvement of a single factor will improve the efficiency of the whole analytical system. For the example of uranium determination in process chemicals such as concentrated HF and HNO₃ the improvement or deterioration of the factors given above is demonstrated. The applied methods are matrix removal by evaporation, highly efficient nebulization with a USN, isotope dilution and use of a double-focusing instrument (ICP-SFMS_LR). The increase or decrease of each factor is compared to conventional nebulization ICP-QMS. To take full advantage of each single method, they can be combined with each other. Possible drawbacks of a single method are compensated by another method. Detection limits for uranium in concentrated process chemicals in the sub-pg/g range can be achieved.     

An Effective Zeta Potential Fitting Model for Sphere-Plate Interaction Force in Nanoparticle Suspensions

The silica sphere-plate interaction forces in zirconia nanoparticle suspensions have been successfully measured to explain how negligibly charged silica microspheres can be stabilized through the addition of highly charged zirconia nanoparticles. However, the influence of nanoparticle volume fraction on the stabilization as well as how various forces (the attractive van der Waals force, repulsive electrostatic force, and depletion force) contribute to the total interaction force still remains unclear. Therefore, an effective zeta potential fitting model is developed to explain the experimental interaction force curves based on a variable effective Debye length and a measured effective zeta potential using a continuum assumption.