Über die quantitative Bestimmung von Quecksilber(II)ionen durch katalytische Zersetzung von Ferrocyanid.

Zusammenfassung Die unter katalytischer Wirkung von Quecksilber(II)ionen ablaufende Umsetzung von Ferrocyanid zu Berlinerblau wurde als quantitative kolorimetrische Methode zur Bestimmung von Quecksilber(II) in Konzentrationen von 5 bis 50g/ml ausgearbeitet.

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Summary The partial oxidation of ferrocyanide to Prussian blue accomplished under the catalytic action of mercury(II) ions has been developed into a quantitative method for the determination of mercury(II) in concentrations of 5 to 50g/ml.

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Résumé L'oxydation partielle du ferrocyanure en bleu de Berlin sous l'influence catalytique des ions Hg(II) a été mise au point comme méthode de dosage des ions Hg(II) à des concentrations de 5 à 50g/ml.

     

Determination of crack growth kinetics in non-reinforced semi-crystalline thermoplastics using the linear elastic fracture mechanics (LEFM) approach

The aim of this study was to find a satisfactory method to characterize the fatigue crack growth behavior of non-reinforced, semi-crystalline thermoplastic polymers using linear elastic fracture mechanics (LEFM). For this, crack growth curves (crack length versus cycle number) as well as crack growth kinetics curves (crack growth rate da/dN versus amplitude stress intensity factor ΔK) had to be generated. As methods suggested by ISO 15850 and ASTM E 647-11 failed to provide satisfactory results for the crack growth curves, a more advanced method was searched for and finally found in the literature. Regarding the crack growth kinetics curve, the idea of the calculation was based on methods recommended in ISO 15850 and ASTM E 647-11. However, these methods had to be considerably modified and improved in order to get accurate results with little scatter. The whole methodology was developed and verified with fatigue crack growth tests on two semi-crystalline thermoplastics (polyoxymethylene POM and polyetheretherketone PEEK).     

Catalysis and Electron Transfer in De Novo Designed Helical Scaffolds

The relationship between protein structure and function is one of the greatest puzzles within biochemistry. De novo metalloprotein design is a way to wipe the board clean and determine what is required to build in function from the ground up in an unrelated structure. This Review focuses on protein design efforts to create de novo metalloproteins within alpha‐helical scaffolds. Examples of successful designs include those with carbonic anhydrase or nitrite reductase activity by incorporating a ZnHis₃ or CuHis₃ site, or that recapitulate the spectroscopic properties of unique electron‐transfer sites in cupredoxins (CuHis₂Cys) or rubredoxins (FeCys₄). This work showcases the versatility of alpha helices as scaffolds for metalloprotein design and the progress that is possible through careful rational design. Our studies cover the invariance of carbonic anhydrase activity with different site positions and scaffolds, refinement of our cupredoxin models, and enhancement of nitrite reductase activity up to 1000‐fold.     

Bose-Einstein correlations for pions produced inp p collisions at 360 GeV/c

Zeitschrift für Physik C Particles and Fields - Correlations among identically charged pions were measured for pions produced inp p collisions at 360 GeV/c using the EHS spectrometer. The...     

The longitudinal asymmetry of the interplanetary perturbation producing Forbush decreases

Summary It is well known that type-IV solar flares occurring between 0° and 40° East of the central meridian can produce the largest Forbush decreases observed at the Earth,i.e. inside the Forbush decrease modulated region the maximum cosmic-ray modulation is observed in the West (∼20° W) of the flare’s meridian plane. A flare-produced perturbation asymmetric in longitude is required in order to explain this asymmetry. The analysis of the two-step Forbush decreases shows that the first step of the decrease is symmetric with respect to the flare’s meridian plane and it is due to the shock wave which is observed ahead of the interplanetary perturbation; on the contrary the second step is strongly asymmetric, the maximum amplitude being observed at ∼30° W of the flare’s meridian plane, and it seems to be due to the magnetic perturbation following the shock; this perturbation is an irregular and compressed magnetic field, the maximum magnetic-field magnitude is found to be placed West of the flare’s meridian plane. The total Forbush decrease amplitude is correlated (correlation coefficient 0.96) with a perturbation parameter which accounts for the ?strength? of the shock and of the following magnetic perturbation. The first step of the decrease is correlated (correlation coefficient 0.88) with the shock ?strength?.

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Riassunto è ben noto che i brillamenti solari accompagnati da radioemissione di tipo IV nell’intervallo 0°–40° est possono produrre le maggiori diminuzioni di Forbush osservate alla terra; cioè, dentro la regione interplanetaria interessata dalla dimizuzione di Forbush la massima modulazione dei raggi cosmici è osservata a circa 20° ovest dal piano meridiano del brillamento solare. Per spiegare questa asimmetria si richiede l’esistenza di una perturbazione interplanetaria generata da brillamento che sia di tipo asimmetrico. L’analisi delle diminuzioni di Forbush ?a due gradini? mostra che la prima diminuzione ha una dipendenza simmetrica rispetto al piano meridiano del brillamento ed è dovuta all’onda d’urto che è osservata all’inizio della perturbazione stessa. La seconda diminuzione, al contrario, è fortemente asimmetrica poiché la massima ampiezza è osservata a circa 30° ovest del piano meridiano del brillamento; essa sembra essere dovuta alla perturbazione magnetica (caratterizzata dal campo magnetico compresso e irregolare) che segue l’onda d’urto; la massima ampiezza del campo magnetico si trova a ovest del piano meridiano del brillamento. L’ampiezza totale delle diminuzioni di Forbush è correlata (coefficiente di correlazione 0.96) con un parametro empirico della perturbazione che tiene conto dell’importanza dell’onda d’urto e della perturbazione magnetica che segue, mentre il primo ?gradino? della diminuzione è correlato (coefficiente di correlazione 0.88) soltanto con il parametro dell’onda d’urto.

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Ррзюме Хорошо известно, что солнечные вспышки типа IV, возникающие в интервале между 0° и 40° к востоку от центрального меридиана, могут порождать большие убывания форбуша, наблюдаемые на Земле, т.е. внутри модулированной области убывания форбуша наблюдается максимальная модуляция космических лучей около 20° к западу от меридианной плоскости солнечной вспышки. Для объяснения этой асимметрии требуется существование межпланетного возмущения, образованного вспышкой, которое является асимметричным по долготе. Анализ двух-ступенчатых убываний форбуша показывает, что первая ступень убывания является симметричной относительно меридианной плоскости вспышки и обусловлена ударной волной, которая наблюдается перед межпланетным возмущением; напротив, вторая ступень является сильно асимметричной, максимум интенсивности наблюдается около 30° к западу от меридианной плоскости вспымки, и, по-видимому, является результатом магнитного возмущения после ударной волны; это возмущение является иррегулярным и вызывает сжатие магнитного поля. Максимум амплитуды магнитного поля расположен к западу от меридианной плоскости вспышки. Полная амплитуда убывания форбуша коррелирует (коэффициент корреляции 0.96) с параметром возмущения, который характеризует ?интенсивность? ударной волны и последующее возмущение магнитного поля. Первая ступень убывания Форбуша коррелирует (коэффициент корреляции 0.88) только с ?интенсивностью? ударной волны.

     

A class of planar well-covered graphs with girth four

A well-covered graph is a graph in which every maximal independent set is a maximum independent set; Plummer introduced the concept in a 1970 paper. The notion of a 1-well-covered graph was introduced by Staples in her 1975 dissertation: a well-covered graph G is 1-well-covered if and only if G - v is also well covered for every point v in G. Except for K₂ and C₅, every 1-well-covered graph contains triangles or 4-cycles. We show that all planar 1-well-covered graphs of girth 4 belong to a specific infinite family, and we give a characterization of this family. © 1995 John Wiley & Sons, Inc.     

Exploring Network Formation of Tough and Biocompatible Thiol‐yne Based Photopolymers

This work deals with the in‐depth investigation of thiol‐yne based network formation and its effect on thermomechanical properties and impact strength. The results show that the bifunctional alkyne monomer di(but‐1‐yne‐4‐yl)carbonate ( DBC ) provides significantly lower cytotoxicity than the comparable acrylate, 1,4‐butanediol diacrylate ( BDA ). Real‐time near infrared photorheology measurements reveal that gel formation is shifted to higher conversions for DBC /thiol resins leading to lower shrinkage stress and higher overall monomer conversion than BDA . Glass transition temperature (T_g), shrinkage stress, as well as network density determined by double quantum solid state NMR, increase proportionally with the thiol functionality. Most importantly, highly cross‐linked DBC /dipentaerythritol hexa(3‐mercaptopropionate) networks (T_g ≈ 61 °C) provide a 5.3 times higher impact strength than BDA , which is explained by the unique network homogeneity of thiol‐yne photopolymers.