Long-term stability of the elemental composition in biological materials

Summary Lyophilized and radiation sterilized biological certified reference materials (CRMs) are believed to be stable in their chemical composition. Generally, the certifying agencies consider the certificates of these biological CRMs valid for a 5-year shelf life, i.e., apart from measurable moisture content, the chemical composition should not change during that time. The long-term behavior of fresh frozen material is not known. In this study the elemental compositions of the Bovine Liver Standard Reference Material (SRM 1577) and human liver tissue samples are evaluated over a time period of more than 7 years. The concentrations of selected elements were determined by neutron activation analysis at various times. The initial evaluation of zinc, selenium and arsenic results gives no indication of changes during 7 years storage of fresh frozen tissues, however, a trend towards lower arsenic concentrations has been observed in SRM 1577 during a 10-year period.

---

Langzeitstabilität der Elementzusammensetzung in biologischen Materialien

     

Near-field contaminant dispersion from an elevated line-source

This paper is a sequel to Sullivan and Yip [1] where a versatile solution-scheme for the three-dimensional, convective-diffusion equation was presented. Measurements of the contaminant concentration field that results from an elevated line-source within a rough-walled, turbulent, boundary-layer by Raupach and Legg [2] are shown to be in good agreement with the concentration values produced by this application of that solution-scheme.

---

Zusammenfassung In einer früheren Arbeit haben Sullivan und Yip eine vielseitig brauchbare Lösungsmethode für die dreidimensionale konvektive Diffusionsgleichung vorgestellt. Die vorliegende Fortsetzung jener Arbeit vergleicht gerechnete Resultate mit Messungen. Durch Raupach und Legg gemessene Schadstoff-Konzentrationen in einer turbulenten Grenzschicht an einer rauhen Wand stimmen gut mit den gerechneten Werten überein. Der Schadstoff wird durch eine lineare Quelle ausgeschieden, die parallel und erhöht über der Wand angebracht ist.

     

Photochemistry of tetramethyl-4-pyrone in alcohol solvents

Irradiation of tetramethyl-4-pyrone in alcohol solvents leads to the formation of tetramethyl-2-pyrone and to a variety of cyclopent-2-enone and cyclopent-3-enone solvent adducts. The structure and mode of product formation is consistent with photochemical generation of a short-lived 2,6-bridged oxabicyclohexenyl zwitterion which undergoes sigmatropic rearrangement to a longer-lived epoxycyclopentenone. Although the zwitterion is efficiently trapped by methanol solvent, in less nucleophilic alcohol solvents it rearranges to the epoxycyclopentenone which isomerizes to the 2-pyrone or reacts with the alcohol solvent to form the observed solvent adducts.     

Trace quantitation of 4-hydroxy-2-nonenal in biological samples as its oxime-bis-tert.-butyldimethylsilyl derivative using 3-hydroxynonanal as an internal standard.

A gas chromatographic-mass spectrometric method for the determination of the lipid aldehyde 4-hydroxy-2-nonenal (4HNE) in trace quantities is described. The method utilizes the reaction of aldehydes with hydroxylamine leading to the formation of the oxime derivative. The aldehydes are recovered by octadecylsilyl solid-phase extraction and converted to the bis-tert.-butyldimethylsilyl derivatives for analysis using electron ionization. A novel 4HNE analogue, 3-hydroxynonanal, has been synthesized and is used as an internal standard. A limit of detection of approximately 1 pmol of 4 HNE in preparations of approximately 2.10(6) cells or 0.5 ml of whole blood, plasma or serum was observed. Standard addition analysis indicates that the method is accurate at these levels. Replicate analysis of the National Institutes of Standards and Technology Standard Reference Material SRM 909 indicates an average in-run precision of 8.1% and a between-run precision of 13.5% at an average concentration of 82.1 pmol/ml of reconstituted material.     

Use of transmitted color to calibrate the thickness of silicon samples

In preparing silicon-based semiconductors for transmission electron microscopy (TEM), it has been widely observed that a backlit silicon sample displays a series of colors in the thinnest regions. These colors results from absorption and optical interference of light within the silicon sample and depend upon the type of light source and the silicon sample thickness. These colors can range from deep red for thickness ≥5 μm, through orange and yellow in the thinner regions, to essentially colorless at the thinnest regions. In this work we present the first direct measurement of silicon color versus thickness and discuss the factors that influence this relationship.     

LowpT phenomena in A+A and p+A collisions at mid-rapidity

CERN experiment NA44 measures pion and kaon distributions atpT=0–320 MeV/c at midrapidity in p+A and A+A collisions at 450 and 200A GeV/c, respectively. Pion production from p+Pb and A+A is slightly enhanced at lowpT relative to p+Be, but less than observed at target rapidity. The lowpT behavior can be understood in the context of the RQMD model as arising from baryonic resonance decays.     

An antimicrobial sesterterpene from a Palauan sponge

An unidentified sponge from Palau contained the antimicrobial sesterpene $\text{1}$ that was identified by interpretation of spectral data and conversion into a degradation product of illimaquinone.