The Escherichia coli RnlA–RnlB toxin–antitoxin complex: production, characterization and crystallization

The Escherichia coli rnlAB operon encodes a toxin–antitoxin module that is involved in protection against infection by bacteriophage T4. The full-length RnlA–RnlB toxin–antitoxin complex as well as the toxin RnlA were purified to homogeneity and crystallized. When the affinity tag is placed on RnlA, RnlB is largely lost during purification and the resulting crystals exclusively comprise RnlA. A homogeneous preparation of RnlA–RnlB containing stoichiometric amounts of both proteins could only be obtained using a His tag placed C-terminal to RnlB. Native mass spectrometry and SAXS indicate a 1:1 stoichiometry for this RnlA–RnlB complex. Crystals of the RnlA–RnlB complex belonged to space group C2, with unit-cell parameters a = 243.32, b = 133.58, c = 55.64 Å, β = 95.11°, and diffracted to 2.6 Å resolution. The presence of both proteins in the crystals was confirmed and the asymmetric unit is likely to contain a heterotetramer with RnlA2:RnlB2 stoichiometry.

Facile Synthesis of Novel Prussian Blue–Lipid Nanocomplexes

Prussian blue (PB) is known for its multiple applications ranging from fine arts to therapeutics. More recently, PB nanoparticles have been pointed to as appealing photothermal agents (PA) when irradiated with wavelengths corresponding to the biological windows, namely regions located in the near infrared (NIR) zone. In addition, the combination of PB with other components such as phospholipids boosts their therapeutical potential by facilitating, for instance, the incorporation of drugs becoming suitable drug delivery systems. The novelty of the research relies on the synthesis procedure and characterization of hybrid lipid–PB nanoparticles with a high yield in a friendly environment suitable for photothermal therapy. This goal was achieved by first obtaining insoluble PB coated with oleylamine (OA) to facilitate its combination with lipids. The resulting lipid–PB complex showed a monomodal distribution of sizes with an overall size of around 100 nm and a polydispersity index of about 0.200. It highlights one critical step in the synthesis procedure that is the shaking time of the mixture of PB–OA nanoparticles with the lipid, which was found to be 48 h. This time assured homogeneous preparation without the need of further separation stages. Samples were stable for more than three months under several storage conditions.

Bohren von ausferritischem Gusseisen mit Kugelgraphit*/Drilling of austempered ductile iron – Impact of the cutting edge geometry on tool wear and machining result

Die Schneidkantenpräparation erlaubt ein gezieltes Anpassen des Werkzeugs an die Bearbeitungsaufgabe bei der Zerspanung. Homogene Präparationen können dabei entweder auf hohe Belastungen des Werkzeugs oder ein optimiertes Bearbeitungsergebnis im Sinne der Oberfläche ausgelegt werden. Mittels inhomogener Schneidkantenpräparation können die unterschiedlichen Anforderungen entlang des Eingriffs individuell in einem Werkzeug vereint werden. Im Beitrag wurden die Schneidkanten eines Wendeschneidplatten-Bohrwerkzeugs unterschiedlich homogen und inhomogen präpariert. Neben dem Werkzeugverschleiß wurde das Prozessergebnis beim Bohren von ausferritischem Gusseisen mit Kugelgraphit (ADI) 900 untersucht.   By using cutting edge preparation, tools can be tailored to the machining process. A homogeneous preparation can either be designed for high loads in the machining process or an optimized machining result on the surface. In contrast, an inhomogeneous cutting edge design can individually be designed to the machining task. In the article, the cutting edges of tungsten carbide indexable inserts were prepared homogeneous and inhomogeneous. Tool wear and machining result during drilling austempered ductile iron (ADI) 900 was investigated.

Drehen von ausferritischem Gusseisen*/Turning of austempered ductile iron – Impact of inhomogeneous cutting edge geometry on wear mechanism and machining result

Mit Schneidkantenpräparation kann das Werkzeug im Zerspanprozess an die Bearbeitungsaufgabe angepasst werden. Homogene Präparationen können dabei entweder auf hohe Belastungen des Werkzeugs oder ein optimiertes Bearbeitungsergebnis im Sinne der Oberfläche ausgelegt werden. In diesem Beitrag wurden die Schneidkanten von Hartmetall-Wendeschneidplatten unterschiedlich inhomogen präpariert, um den unterschiedlichen Anforderungen entlang des Eingriffs Rechnung zu tragen. Neben der Werkzeugstandzeit wurde das Prozessergebnis beim Außenlängs-Runddrehen von ausferritischem Gusseisen (ADI) 900 untersucht.   The preparation of cutting edges allows for tools to be tailored to the machining process. A homogeneous preparation can either be designed for high loads in the machining process or an optimized machining result on the surface. In this article, the cutting edges of tungsten carbide indexable inserts were prepared inhomogeneously and thus individually matched to the machining task. Tool life and machining performance while turning austempered ductile iron (ADI) 900 were investigated.