Carbaborane‐Substituted 1,2,3‐Triphospholanes and 1‐Aza‐2,5‐diphospholane: New Synthetic Approaches

New phosphorus‐containing, five‐membered P,P,P and P,N,P heterocycles were synthesized and fully characterized. The P,P,P heterocycles, 1,2,3‐triphospholanes, can be synthesized by two different facile pathways, whereas the P,N,P compound, a 1‐aza‐2,5‐diphospholane, can only be obtained with silylamine.     

Selective Uptake of Cylindrical Poly(2‐Oxazoline) Brush‐AntiDEC205 Antibody‐OVA Antigen Conjugates into DEC‐Positive Dendritic Cells and Subsequent T‐Cell Activation

To achieve specific cell targeting by various receptors for oligosaccharides or antibodies, a carrier must not be taken up by any of the very many different cells and needs functional groups prone to clean conjugation chemistry to derive well‐defined structures with a high biological specificity. A polymeric nanocarrier is presented that consists of a cylindrical brush polymer with poly‐2‐oxazoline side chains carrying an azide functional group on each of the many side chain ends. After click conjugation of dye and an anti‐DEC205 antibody to the periphery of the cylindrical brush polymer, antibody‐mediated specific binding and uptake into DEC205⁺‐positive mouse bone marrow‐derived dendritic cells (BMDC) was observed, whereas binding and uptake by DEC205^? negative BMDC and non‐DC was essentially absent. Additional conjugation of an antigen peptide yielded a multifunctional polymer structure with a much stronger antigen‐specific T‐cell stimulatory capacity of pretreated BMDC than application of antigen or polymer–antigen conjugate.     

Arc cathode spots: Their mechanism and motion

Arc spots are usually highly unstable and jump statistically over the cathode surface. In a magnetic field parallel to the surface, they preferably move in the retrograde direction, i.e., opposite to the Lorentzian rule. If the field is inclined with respect to the surface, the spots drift away at a certain angle with respect to the proper retrograde direction (Robson drift motion). The phenomenon are explained by a unique stability theory     

Phase I and II metabolites of speciogynine, a diastereomer of the main Kratom alkaloid mitragynine, identified in rat and human urine by liquid chromatography coupled to low- and high-resolution linear ion trap mass spectrometry

Mitragyna speciosa (Kratom in Thai), a Thai medical plant, is misused as herbal drug of abuse. Besides the most abundant alkaloids mitragynine (MG) and paynantheine (PAY), several other alkaloids were isolated from Kratom leaves, among them the third abundant alkaloid is speciogynine (SG), a diastereomer of MG. The aim of this present study was to identify the phase I and II metabolites of SG in rat urine after the administration of a rather high dose of the pure alkaloid and then to confirm these findings using human urine samples after Kratom use. The applied liquid chromatography coupled to low- and high-resolution mass spectrometry (LC-HRMS-MS) provided detailed information on the structure in the MS(n) mode particularly with high resolution. For the analysis of the human samples, the LC separation had to be improved markedly allowing the separation of SG and its metabolites from its diastereomer MG and its metabolites. In analogy to MG, besides SG, nine phase I and eight phase II metabolites could be identified in rat urine, but only three phase I and five phase II metabolites in human urine. These differences may be caused by the lower SG dose applied by the user of Kratom preparations. SG and its metabolites could be differentiated in the human samples from the diastereomeric MG and its metabolites comparing the different retention times determined after application of the single alkaloids to rats. In addition, some differences in MS(2) and/or MS(3) spectra of the corresponding diastereomers were observed.     

Determination of the elongational viscosity of polymer melts by melt spinning experiments. A comparison with different experimental techniques

In this work, melt spinning experiments were tentatively used for the determination of the elongational viscosity of polymer melts at different levels of tensile strain and strain rate. The materials examined were two high-density polyethylene grades for blow moulding with similar number-average molecular mass but different polydispersity index. The data from melt spinning tests were compared with transient extensional viscosity data obtained by uniform isothermal tensile tests, performed by means of an extensional rheometer, as well as with those produced by converging flow tests (Cogswell model). The results showed that for high strain and strain rate levels, the melt spinning experiments provide elongational viscosity data quite close to the transient extensional viscosity values obtained from the tensile tests.     

Ageing of Alkylthiol‐Stabilized Gold Nanoparticles

The ageing of spherical gold nanoparticles having 6‐nm‐diameter cores and a ligand shell of dodecanethiol is investigated under different storage conditions. Losses caused by agglomeration and changes in optical particle properties are quantified. Changes in colloidal stability are probed by analytical centrifugation in a polar solvent mixture. Chemical changes are detected by elementary analysis of particles and solvent. Fractionation occurs under all storage conditions. Ageing is not uniform but broadens the property distributions of the particles. Small‐number statistics in the ligand shell density and the morphological heterogeneity of particles are possible explanations. Washing steps exacerbate ageing, a process that could not be fully reversed by excess ligands. Dry storage is not preferable to storage in solvent. Storage under inert argon atmosphere reduces losses more than all other conditions but could not prevent it entirely.     

Syntheses of N10‐substituted 7‐Arylpyrrolo[2,1‐c]‐[1,4]benzodiazepine‐5,11‐diones

Pyrrolo[2,1‐c][1,4]benzodiazepine‐5,11‐dione and its 7‐bromo derivative were alkylated at the N10 atom applying various methods. The resulting products were subjected to Suzuki–Miyaura reactions using a catalyst system consisting of Pd(Cl)₂(PPh₃)₂ and sodium tert‐butanolate in toluene. Results of an X‐ray single crystal analysis are presented.     

Preparation of raspberry-like nanocapsules by the combination of Pickering emulsification and solvent displacement technique

Well-defined raspberry-like nanocapsules were prepared by the combination of Pickering emulsification and solvent displacement technique by using silica particles as stabilizer and hexadecane (HD) as soft template. The formation of the capsule morphology is caused by the phase separation of poly(styrene-co-4-vinyl pyridine) (poly(St-co-4-VP)) in the droplets due to the diffusion of good solvent for the (co)polymer to the aqueous continuous phase. The size of capsules was successfully reduced from tens of micrometers in the dispersion by simply stirring to the nanorange by the employment of sonication and Ostwald ripening. The formation of silica-particles-armored nanocapsules was confirmed by transmission electron microscopy (TEM), high-resolution scanning electron microscopy (HRSEM), dynamic light scattering (DLS), and zeta potential measurement. The colloidal stability and particle properties, including size and morphology, depend on the amount of HD, and copolymers, the sonication time, the dispersion pH value, the type of solvent, and the copolymer composition.