In vitro biological performances of phosphorylcholine-grafted ePTFE prostheses through RFGD plasma techniques

Arterial prostheses made of microporous Teflon (ePTFE) are currently used in vascular surgery as bypasses for small and medium vessels. However, several clinical complications, such as thrombosis, frequently occur in these prostheses when implanted in humans. In this work, an original strategy was developed to improve the hemocompatibility of ePTFE prostheses, based on glow-discharge surface modification followed by chemical grafting of phosphorylcholine, known for its hemocompatible properties. This procedure leads to a covalent attachment of the molecules, therefore preventing their removal by shear stress induced by blood flow at the implant wall. The improvement of the blood compatibility properties of the modified ePTFE arterial prostheses have been investigated by in vitro tests such as thromboelastography, neutrophil adsorption, platelet aggregation, and cell cultures. These in vitro tests put in evidence that thrombogenicity index, platelet aggregation, and neutrophil adhesion were decreased by the molecule grafted on the prostheses. Moreover, the cell growth on the surface of the PRC-grafted prostheses was greatly enhanced in comparison to the virgin prosthesis. Based on these results, it could be concluded that PRC grafting on ePTFE prostheses permit to improve in vitro hemocompatibility and biocompatibility in comparison with their virgin counterpart.     

Laboratory computer systems and the role of the human interface

The importance of the “human interface” between the operator and a laboratory computer system is emphasized. Some rules for communication through dialogue programs and command languages as well as for the presentation of computer output are given. The degree of automation of the evaluation of analytical data versus interactive treatment is discussed.     

Bakteriochlorophyll aGg und Bakteriophäophytin aP in den photosynthetischen Reaktionszentren von rhodospirillum rubrum G-9+

Bacteriochlorophyll a_Gg and Bacteriopheophytin a_p in Photosynthetic Reaction Centers from Rhodospirillum rubrum G-9⁺ In photosynthetically active reaction centers from Rhodospirillum rubrum G-9⁺, the magnesium complex bacteriochlorophyll a contains geranylgeraniol as the alcohol component, while the metal-free bacteriopheophytin a contains phytol instead. These pigments bacteriochlorophyll a_Gg ( 4 ) and bacteriopheophytin a_P ( 1 ) were isolated from reaction center preparations in a ratio of 2:1 and (after demetallation of 4 ) identified as bacteriopheophytin a_Gg ( 2 ), and a_P ( 1 ) by comparison with authentic samples (UV./VIS., CD. and mass spectra as well as mixed HPLC.).     

A Note on One-Dimensional Stochastic Equations

We consider the stochastic equation

Perylenetetracarboxylic Diimide as Diffusion-Less Electrode Material for High-Rate Organic Na-Ion Batteries

In this work 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) is investigated as electrode material for organic Na-ion batteries. Since PTCDI is a widely used industrial pigment, it may turn out to be a cost-effective, abundant, and environmentally benign cathode material for secondary Na-ion batteries. Among other carbonyl pigments, PTCDI is especially interesting due to its high Na-storage capacity in combination with remarkable high rate capabilities. The detailed analysis of cyclic voltammetry measurements reveals a diffusion-less mechanism, suggesting that Na-ion storage in the PTCDI film allows for exceptionally fast charging/discharging rates. This finding is further corroborated by galvanostatic sodiation measurements at high rates of 17 C (2.3 A g⁻¹), showing that 57 % of the theoretically possible capacity of PTCDI, or 78 mAh g⁻¹, are attained in only 3.5 min charging time.     

The Even/Odd Disparity in Organic Compounds

There are more organic compounds with an even number of carbon atoms than with an odd number. This disparity could result mainly from the methods used in synthetic chemistry to build large molecules from smaller ones. Samples of C₂₈, C₄₇ and C₄₈ compounds have been examined in this context.