Inhibitoren der Korrosion (8) Über die Abhängigkeit der Korrosionsinhibierung des Eisens in Salzsäure von der Struktur quartärer Phosphoniumsalze

Inhibition of the corrosion of iron in hydrochlorid acid as a function of the structure of quaternary phosphonium salts In the case of quaternary phospho-nium salts there is no direct relation between their inhibiting power in deaer-ated acid media and the polarographi-cally determined reduction potentials. The inhibiting effect can in a first line be attributed to sterical factors con-nected with the fragments formed after incorporation of two electrons and be-coming fixed to the iron surface. Biphosphonium salts having saturated or unsaturated bridges are excellent in-hibitors under the conditions mentioned. Most efficient are biphosphonium salts having chaines of 4 to 10 methylene groups between the phosphonium cen-tres. The rigid p-phenylene radikal is less suitable as a linking principle. Phe-nyl phosphine and diphenyl phosphine in low concentrations accelerate corro-sion and exhibit a protective effect only in higher concentrations. Polymers having incorporated phos-phonium centres are only moderate inhibitors when compared to biphospho-nium salts. The synthesis is outlined and some physical and chemical properties are given.     

Inhibitoren der Korrosion 10 (1). Nachweis der Sekundärinhibition durch Allyl-triphenyl-phosphonium- bzw. arsoniumbromid und N-Allyl-chinaldiniumbromid

Corrosion inhibitors (10) Demonstration of the secondary inhibition by allyl triphenyl phosphonium and arsonium bromides and N-ally1 quinaldinium bromide Triphenyl allyl phosphonium (1) and arsonium (2) salts as well as allyl quinaldinium bromide (4) are corrosion inhibitors of moderate efficiency. In acid media they are reduced by carfinyl iron powder to yield triphenyl phosphine and triphenyl arsine respectively and quinaldine. The two products mentioned the first form a layer on carbonyl iron and, after extraction, may be identified by gas chromatography. The allyl group is eliminated by iron from 1, 2 and 4, yielding Pro-pene, propane and, probably, cyclopropane. The hydrocarbon quantities determined by gas chromatography are in good agreement with the values found in the gravimetric determination of allyl-onium salts after the reaction. Ally triphenyl phosphonium bromide ( I ) and allyl diphenyl sulfonium tetraborate (3) yield propene and propane in a 1:1 ratio. In the case of (2) and (4) this ratio is shifted to 14:l and 7:l respectively. The hydrocarbon proportion in the gas mix-ture is higher at the beginning of the reaction than toward its end; at the beginning, the Propane:propene ratio is also displaced, the formation of propane having priority.     

Evaluation of a Novel Thiol–Norbornene-Functionalized Gelatin Hydrogel for Bioprinting of Mesenchymal Stem Cells

Introduction: Three-dimensional bioprinting can be considered as an advancement of the classical tissue engineering concept. For bioprinting, cells have to be dispersed in hydrogels. Recently, a novel semi-synthetic thiolene hydrogel system based on norbornene-functionalized gelatin (GelNB) and thiolated gelatin (GelS) was described that resulted in the photoclick hydrogel GelNB/GelS. In this study, we evaluated the printability and biocompatibility of this hydrogel system towards adipose-tissue-derived mesenchymal stem cells (ASCs). Methods: GelNB/GelS was synthesized with three different crosslinking densities (low, medium and high), resulting in different mechanical properties with moduli of elasticity between 206 Pa and 1383 Pa. These hydrogels were tested for their biocompatibility towards ASCs in terms of their viability, proliferation and differentiation. The extrusion-based bioprinting of ASCs in GelNB/GelS-high was performed to manufacture three-dimensional cubic constructs. Results: All three hydrogels supported the viability, proliferation and chondrogenic differentiation of ASCs to a similar extent. The adipogenic differentiation of ASCs was better supported by the softer hydrogel (GelNB/GelS-low), whereas the osteogenic differentiation was more pronounced in the harder hydrogel (GelNB/GelS-high), indicating that the differentiation fate of ASCs can be influenced via the adaption of the mechanical properties of the GelNB/GelS system. After the ex vivo chondrogenic differentiation and subcutaneous implantation of the bioprinted construct into immunocompromised mice, the production of negatively charged sulfated proteoglycans could be observed with only minimal inflammatory signs in the implanted material. Conclusions: Our results indicate that the GelNB/GelS hydrogels are very well suited for the bioprinting of ASCs and may represent attractive hydrogels for subsequent in vivo tissue engineering applications.     

Paracetamol poisoning in the north east of England: presentation, early management and outcome

1. Paracetamol is increasingly involved in self-poisoning in the United Kingdom and remains a common cause of fatal poisoning. 2. To document the epidemiology and early management of paracetamol poisoning data were collected on consecutive patients with suspected paracetamol poisoning presenting to 6 hospitals in the North East of England over 12 weeks in 1994. 3. There were 400 presentations (attendance rate 1.14/10(3) population/yr) involving 343 persons (45% male). Paracetamol concentrations at 4 h correlated weakly with reported paracetamol dose (R = 0.49, P < 0.0001) and were similar comparing those treated and not treated by gastric decontamination. 4. In 38 (9%) cases paracetamol concentrations were above the appropriate nomogram treatment line, including 3% and 20% of patients who reported ingesting less than and more than 12 g respectively. In 21 patients acetylcysteine treatment was deferred until admission to the ward, the mean delay involved was 2.8 h. 5. One patient died, from arrhythmias caused by co-ingested dothiepin. 6. Paracetamol poisoning is common. Most cases do not have potentially toxic plasma paracetamol concentrations, but those who do often present late and antidotal treatment may be delayed inappropriately.     

Evaluation of the Interaction between Phosphohistidine Analogues and Phosphotyrosine Binding Domains

We have investigated the interaction of peptides containing phosphohistidine analogues and their homologues with the prototypical phosphotyrosine binding SH2 domain from the eukaryotic cell signalling protein Grb2 by using a combination of isothermal titration calorimetry and a fluorescence anisotropy competition assay. These investigations demonstrated that the triazole class of phosphohistidine analogues are capable of binding too, suggesting that phosphohistidine could potentially be detected by this class of proteins in vivo.