Über den Einbau von Nickel in die Alkalichloride

By means of the method of P. Brauer the energy of built in Ni⁺⁺-ions in the crystals of LiCl, NaCl and KCl was calculated. The results let understand the differences in the content of nickel in the mentioned crystals.

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Der Verfasser dankt herzlich Herrn Dr. K. Polák für die wertvollen Diskussionen und Bemerkungen zu dieser Arbeit, Frl. Dipl.-Ing. H. Svobodová für die Durchführung der numerischen Berechnungen und Herrn Dr. K. Funk für die Beistellung der Analysenergebnisse.     

Separation of alpha-amino acid enantiomers by reversed-phase high-performance liquid chromatography after derivatization with o-phthaldialdehyde and a sodium salt of 1-thio-beta-D-glucose

A sensitive system for D,L-amino acid analysis has been developed, using fluorescence derivatization with o-phthaldialdehyde in the presence of sodium salt of 1-thio-beta-D-glucose. The reagents rapidly form fluorescent diastereoisomeric derivatives with primary amino acids. These derivatives are efficiently separated on a conventional reversed-phase column with an analysis time of 60 min. Simultaneous determination of enantiomers of various amino acids was achieved by a simple binary gradient elution with methanol in 0.05 M aqueous sodium acetate.     

Covalent labeling of a chromatin reader domain using proximity-reactive cyclic peptides

Chemical probes for chromatin reader proteins are valuable tools for investigating epigenetic regulatory mechanisms and evaluating whether the target of interest holds therapeutic potential. Developing potent inhibitors for the plant homeodomain (PHD) family of methylation readers remains a difficult task due to the charged, shallow and extended nature of the histone binding site that precludes effective engagement of conventional small molecules. Herein, we describe the development of novel proximity-reactive cyclopeptide inhibitors for PHD3—a trimethyllysine reader domain of histone demethylase KDM5A. Guided by the PHD3–histone co-crystal structure, we designed a sidechain-to-sidechain linking strategy to improve peptide proteolytic stability whilst maintaining binding affinity. We have developed an operationally simple solid-phase macrocyclization pathway, capitalizing on the inherent reactivity of the dimethyllysine ε-amino group to generate scaffolds bearing charged tetraalkylammonium functionalities that effectively engage the shallow aromatic ‘groove’ of PHD3. Leveraging a surface-exposed lysine residue on PHD3 adjacent to the ligand binding site, cyclic peptides were rendered covalent through installation of an arylsulfonyl fluoride warhead. The resulting lysine-reactive cyclic peptides demonstrated rapid and efficient labeling of the PHD3 domain in HEK293T lysates, showcasing the feasibility of employing proximity-induced reactivity for covalent labeling of this challenging family of reader domains.

We describe the development of covalent cyclic peptide ligands which target a chromatin methylation reader domain using a proximity-reactive sulfonyl fluoride moiety.     

Investigation of in-medium ω photoproduction

Recent experimental results on the in-medium modification of the ω meson are discussed. The experiment described was performed at the ELSA accelerator facility in Bonn using the combined detector system of Crystal Barrel and TAPS. Theω-meson was identified via the reaction γ+A → ω +X → π⁰ γ +X     

Behaviour of inorganic constituents of municipal sewage sludge during fluidized-bed combustion

The fate of main heavy metals in municipal sewage sludge (As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, and Zn) was investigated using a fluidized-bed reactor. The behaviour of metals in the incinerator was explored by comparing metal contents in the two main ash streams: bottom (in-bed) ash and ash separated by a cyclone (cyclone-catch ash). All metals showed enrichment in the cyclone ash. The ash originating from sewage sludge is thermally quite stable consisting of quartz, hematite, spar(s), mica(s), apatite, and anhydrite. It does not soften nor becomes sticky and does not tend to agglomerate at temperatures up to 950°C.     

Fluidization behavior of oil-contaminated sand

Hydrodynamic behavior of oil-polluted particles of sand was investigated in transparent glass column. The onset of fluidization of sand beds increased with the oil content of the bed. An increase of cohesive forces related to the higher content of liquid (oil) caused deterioration of the quality of fluidization. An empirical correlation was developed to predict the dimensionless gas velocity that keeps the bed of sticky particles fluidized. Results of this work can be employed for the design of fluidized-bed remediation units for oil-polluted sands and soils. An erratum to this article is available at .     

DTA study on lead chloride

The hydrolysis of lead chloride by residual water is responsible for the appearance of a second peak in the DTA curve, due to melting of the eutectic PbCl₂-PbO in repeated measurement runs on the same sample. This effect has previously been misinterpreted as a solid-solid transition in pure PbCl₂.     

Zur Frage der Pb(II)-Komplexe in Gemischten KCl-KBr-Kristallen

The absorption and fluorescent spectra of mixed KCl-KBr crystals with lead admixtures were measured. A comparison with the absorption of analogical mixed solutions showed that the displacement of the absorption band of lead towards longer wave-lengths with increasing content of bromide is caused by the creation of mixed complexes. The latter are also responsible for the fluorescence of the crystals.

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Die Verfasser danken herzlich Herrn Dr. A. Bohun für die wertvollen Diskussionen. Sie danken ferner Frau K. Dolealová für die Durchführung der Absorptionsmessungen der Kristalle und Frau M. Kubovská für die Züchtung der Kristalle.     

Der Einfluss von Chlor auf die Exoelektronenemission und Lumineszenz von NaCl

Zusammenfassung Auf Grund von Versuchsergebnissen, die hauptsächlich an in Chlor erhitzten Kristallen von NaClgewonnen wurden, wird eine Erklärung für das unterschiedliche Auftreten von Hochtemperatur-Emissions-und Lumineszenzmaxima in der Umgebung von 520 und 580 °Kgegeben. Es wird gezeigt, dass die Hauptrolle hier neutrales Chlor spielt, insbesondere wenn es in stöchiometrischem Überschuss (wahrscheinlich als A oder V-Zentren) vorhanden ist. In den Fällen, in denen zwei (gegebenenfalls mehrere) Hochtemperatur-Maximaauftreten, existieren im NaClmindestens zwei (wahrscheinlich mehrere) verschiedene Farbzentren, deren Absorptionsbänder sich bei Raumtemperatur mit dem Band der F-Zentren überdecken. Es werden die Ergebnisse verschiedener Autoren verglichen und die Zuordnung der Tieftemperatur-Thermolumineszenz-maxima um 370 °Kden Farbzentren diskutiert.