Research on refurbishable thermostructural panels for manned lifting entry vehicles

Refurbishable composite thermostructural heat shield panels for manned lifting entry vehicle

Mise au point d'un microscope à effet tunnel

La conception et la réalisation d'un microscope à effet tunnel sont présentées. On discute de la partie mécanique et de la façon de réaliser l'isolation vis-à-vis des vibrations. Le comportement de la boucle d'asservissement qui contrôle la distance pointe-échantillon est analysée en détail. Les effets parasites dus aux perturbations électriques sont également pris en compte. Les possibilités de ce microscope sont démontrées avec quelques images du graphite et de métaux réalisées à l'air

Anticoagulant Management and Synthesis of Hemostatic Proteins during Machine Preservation of Livers for Transplantation

Liver transplantation remains the only curative treatment for patients with end-stage liver disease. Despite a steadily increasing demand for suitable donor livers, the current pool of donor organs fails to meet this demand. To resolve this discrepancy, livers traditionally considered to be of suboptimal quality and function are increasingly utilized. These marginal livers, however, are less tolerant to the current standard cold preservation of donor organs. Therefore, alternative preservation methods have been sought and are progressively applied into clinical practice. Ex situ machine perfusion is a promising alternative preservation modality particularly for suboptimal donor livers as it provides the ability to resuscitate, recondition, and test the viability of an organ prior to transplantation. This review addresses the modalities of machine perfusion currently being applied, and particularly focuses on the hemostatic management employed during machine perfusion. We discuss the anticoagulant agents used, the variation in dosage, and administration, as well as the implications of perfusion for extended periods of time in terms of coagulation activation associated with production of coagulation factors during perfusion. Furthermore, in regard to viability testing of an organ prior to transplantation, we discuss the possibilities and limitations of utilizing the synthesis of liver-derived coagulation factors as potential viability markers

Entropic phase separation of linked beads

We study theoretically a model system of a transient network of microemulsion droplets connected by telechelic polymers and explain recent experimental findings. Despite the absence of any specific interactions between either the droplets or polymer chains, we predict that as the number of polymers per drop is increased, the system undergoes a first order phase separation into a dense, highly connected phase, in equilibrium with dilute droplets, decorated by polymer loops. The phase transition is purely entropic and is driven by the interplay between the translational entropy of the drops and the configurational entropy of the polymer connections between them. Because it is dominated by entropic effects, the phase separation mechanism of the system is extremely robust and does not depend on the particlular physical realization of the network. The discussed model applies as well to other polymer linked particle aggregates, such as nano-particles connected with short DNA linkers

Topical haemostatic agents in liver surgery: do we need them?

AbstractBackgroundWorldwide, partial liver resections are increasingly being performed for primary or secondary hepatic malignancies. There are various techniques to reduce blood loss druing liver surgery. Several topical haemostatic agents have been developed to improve haemostasis of the resection surface and these agents are used more and more, even although the true effects remain unclear.MethodsThe present literature about the use of topical haemostatic agents in liver surgery was reviewed. Furthermore we conducted a Dutch national survey to explore the use of and belief in these agents in liver surgery.ResultsThe Dutch national survey among surgeons showed that topical haemostatic agents are frequently used not only to lower intra-operative blood loss or shorten time to haemostasis, but even more importantly, to reduce resection surface related complications such as bile leakage, postoperative haemorrhage and abscess formation. Although various topical haemostatic agents have been shown to reduce intra-operative time to haemostasis at the resection surface after liver resections, there is no scientific proof that these topical haemostatic agents really reduce resection surface related complications.ConclusionThis review highlights the need for more randomized clinical trials to investigate the efficacy of topical haemostatic agents in reducing resection surface related complications

To robotize chemistry laboratories. An example of organic synthesis: 2-Boc-amino-N-hydroxy-3-phenyl-propionamide

The paper describes the development of periodic modules used for the peptide synthesis of hydroxamic acid. A powder conveyor using the principle of positive weighing distribution is described. Purification is provided using automatic filtration and a liquid— liquid extraction module separation device. Device quality is improved using failure mode and effects analysis

Understanding the core density profile in TCV H-mode plasmas

Results from a database analysis of H-mode electron density profiles on the Tokamak \`a Configuration Variable (TCV) in stationary conditions show that the logarithmic electron density gradient increases with collisionality. By contrast, usual observations of H-modes showed that the electron density profiles tend to flatten with increasing collisionality. In this work it is reinforced that the role of collisionality alone, depending on the parameter regime, can be rather weak and in these, dominantly electron heated TCV cases, the electron density gradient is tailored by the underlying turbulence regime, which is mostly determined by the ratio of the electron to ion temperature and that of their gradients. Additionally, mostly in ohmic plasmas, the Ware-pinch can significantly contribute to the density peaking. Qualitative agreement between the predicted density peaking by quasi-linear gyrokinetic simulations and the experimental results is found. Quantitative comparison would necessitate ion temperature measurements, which are lacking in the considered experimental dataset. However, the simulation results show that it is the combination of several effects that influences the density peaking in TCV H-mode plasmas.Comment: 23 pages, 12 figure