Unusual stability of dyads during photochemical hydrogen production

Dyads for photochemical water splitting often suffer from instability during irradiation with visible light. However, the use of bis(bidentate) phosphines forming a five-membered ring enhances their stability. The coordination of these phosphor based chelates to soft metals like Pd(ii) prolongs the photocatalytic activity to 1000 hours. To avoid contribution to hydrogen production by colloidal metal, a small amount of Hg is added to the reaction mixture. In the course of our investigations, it turned out that colloidal palladium was not able to produce hydrogen under our irradiation conditions. As soon as metallic palladium emerged in our reaction vessels, no further hydrogen production was detected. This is confirmed by the observation that the hydrogen production depends on the kind of ancillary ligands present in the dyads. The first dyads of the type [MI(bpy)2(dppcb)MII(bpy)]4+ are presented (MI = Os, MII = Pd (1); MI = Ru, MII = Pd (2); MI = Os, MII = Pt (3); MI = Ru, MII = Pt (4)). In [Os(bpy)2(dppcb)Pd(dppm)](PF6)4 (5) the ancillary ligand is varied. Furthermore, it is also possible to produce hydrogen in an intermolecular way. Using different bidentate diphosphines instead of a bis(bidentate) tetraphosphine leads to this intermolecular approach, where the chromophore and the water reduction catalyst (WRC) belong now to two molecules. In this case the TON is sensitive to the type of diphosphine, which is only possible if intact molecules act as catalysts and no free palladium(0) is formed

The influence of aminotransferase levels on liver stiffness assessed by Acoustic Radiation Force Impulse Elastography: A retrospective multicentre study.

Background Acoustic Radiation Force Impulse Elastography is a new method for non-invasive evaluation of liver fibrosis. Aim To evaluate the impact of elevated alanine aminotransferase levels on liver stiffness assessment by Acoustic Radiation Force Impulse Elastography. Methods A multicentre retrospective study including 1242 patients with chronic liver disease, who underwent liver biopsy and Acoustic Radiation Force Impulse. Transient Elastography was also performed in 512 patients. Results The best Acoustic Radiation Force Impulse cut-off for predicting significant fibrosis was 1.29 m/s in cases with normal alanine aminotransferase levels and 1.44 m/s in patients with alanine aminotransferase levels > 5 7 the upper limit of normal. The best cut-off for predicting liver cirrhosis were 1.59 and 1.75 m/s, respectively. Acoustic Radiation Force Impulse cut-off for predicting significant fibrosis and cirrhosis were relatively similar in patients with normal alanine aminotransferase and in those with alanine aminotransferase levels between 1.1 and 5 7 the upper limit of normal: 1.29 m/s vs. 1.36 m/s and 1.59 m/s vs. 1.57 m/s, respectively. For predicting cirrhosis, the Transient Elastography cut-offs were significantly higher in patients with alanine aminotransferase levels between 1.1 and 5 7 the upper limit of normal compared to those with normal alanine aminotransferase: 12.3 kPa vs. 9.1 kPa. Conclusion Liver stiffness values assessed by Acoustic Radiation Force Impulse and Transient Elastography are influenced by high aminotransferase levels. Transient Elastography was also influenced by moderately elevated aminotransferase levels

ARFI: from basic principles to clinical applications in diffuse chronic disease—a review

Abstract The many factors influencing the shear wave velocity (SWV) measured with Acoustic Radiation Force Impulse (ARFI) are examined in order to define the most correct examination technique. In particular, attention is given to the information achieved by experimental models, such as phantoms and animal studies. This review targets the clinical applications of ARFI in the evaluation of chronic diffuse disease, especially of liver and kidneys. The contribution of ARFI to the clinical workout of these patients and some possible perspectives are described. Teaching Points • Stiffness significantly varies among normal and abnormal biological tissues. • In clinical applications physical, geometrical, anatomical and physiological factors influence the SWV. • Elastographic techniques can quantify fibrosis, which is directly related to stiffness. • ARFI can be useful in chronic diffuse disease of liver and kidney