Yverdon-les-bains, Switzerland
Yverdon-les-bains, Switzerland
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Neuenschwander B.,Bern University of Applied Sciences | Jaeggi B.,Bern University of Applied Sciences | Schmid M.,Bern University of Applied Sciences | Rouffiange V.,Amplitude Systemes | Martin P.-E.,Y-Parc SA
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

Ultra short laser pulses in the ps or fs regime are used, when high requirements concerning machining quality are demanded. However, beside the quality also the process efficiency denotes a key factor for the successful transfer of this technology into real industrial applications. Based on the ablation law, holding for ultra short pulses with moderate fluences, it has been shown that the volume ablation rate can be maximized with an optimum setting of the laser parameters. The value of this maximum depends on the threshold fluence and the energy penetration depth. Both measures themselves depend on the pulse duration. For metals the dependence of the threshold fluence is well known, it stays almost constant for pulse durations up to about 10 ps and begin then to slightly increase with the pulse duration. The contrary behavior is observed for the energy penetration depth, it decreases over the whole range when the pulse duration is raised from 500 fs to 50 ps. In this paper we will show that the maximum ablation rate can therefore be increased by a factor of 1.5 to 2 when the pulse duration is reduced from 10 ps down to 500 fs. © 2012 SPIE.

Rosario-Amorin D.,CNRS Institute of Molecular Sciences | Gaboyard M.,Y-Parc SA | Clerac R.,CNRS Paul Pascal Research Center | Vellutini L.,CNRS Institute of Molecular Sciences | And 2 more authors.
Chemistry - A European Journal | Year: 2012

The use of dendritic structures for the grafting of core-shell γ-Fe 2O 3/polymer 300 nm superparamagnetic nanoparticles (MNPs) has been performed with four metallodendrons that were functionalized with diphosphinopalladium complexes. The catalytic performance of these nanocatalysts was optimized for the Suzuki C-C cross-coupling reaction. These results demonstrated the importance of optimizing the catalytic efficiency of grafted MNPs by optimizing the dendritic structures and the nature of the peripheral phosphine ligands. All of these nanocatalysts showed remarkable reactivity towards bromoarenes and they were recovered and efficiently reused by magnetic separation with almost no loss of reactivity, even after 25 cycles. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Levasseur P.,Y-Parc SA | Girard A.-M.,Y-Parc SA | Claudon M.,Y-Parc SA | Goossens H.,University of Antwerp | And 3 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2012

The β-lactamase inhibitor avibactam (NXL104) displays potent inhibition of both class A and C enzymes. The in vitro antibacterial activity of the combination ceftazidime-avibactam was evaluated against a clinical panel of Pseudomonas aeruginosa isolates. Avibactam offered efficient protection from hydrolysis since 94% of isolates were susceptible to ceftazidime when combined with 4 μg/ml avibactam, compared with 65% susceptible to ceftazidime alone. Ceftazidime-avibactam also demonstrated better antipseudomonal activity than imipenem (82% susceptibility), a common reference treatment. Copyright © 2012, American Society for Microbiology. All Rights Reserved.

Harbi P.,Y-Parc SA | Thacher T.,Y-Parc SA
Diabetes and Vascular Disease Research | Year: 2013

There are many pathologies and/or surgical situations where understanding how cutaneous capillary blood flow is behaving would be of clinical benefit. Laser Doppler imaging (LDI) has long been considered an ideal candidate for this yet was never widely adopted. The technology was deemed too slow, needing minutes to record one image. Here, we present the use of a new, real-time LDI, which is sensitive enough to resolve pulsatile blood flow in the microcirculation and can record images and videos instantaneously. We show that when comparing the ratios of absolute perfusion images from different regions of the body, remarkably reproducible data can be obtained when looking at a control population of male volunteers. In the future, we plan to add more control and diseased groups, effectively giving the clinician a non-invasive, safe and easy-to-use diagnostic for assessing the extent of microcirculatory disorders and high-risk surgical situations. © The Author(s) 2012.

Meidani H.,Ecole Polytechnique Federale de Lausanne | Jacot A.,Ecole Polytechnique Federale de Lausanne | Jacot A.,Y-Parc SA
Acta Materialia | Year: 2011

A phase-field model has been developed to describe the morphology of pores constrained by a dendritic solid network, and are forced to adopt complex non-spherical shapes. The distribution of the solid, liquid and gas phases was calculated with a multiphase-field approach which accounts for the pressure difference between the liquid and the gas. The model considers the partitioning of the dissolved gas at interfaces, gas diffusion and capillary forces at the solid/liquid, liquid/gas and gas/solid interfaces. The model was used to study the influence of the dendrite arm spacing (DAS) and the solid fraction on the state of a pore. The calculations show that a pore constrained to grow in a narrow liquid channel exhibits a substantially higher mean curvature, a larger pressure and a smaller volume than an unconstrained pore. Comparisons with simple geometrical models indicate that analytical approaches show a good trend but tend to underestimate the pore curvature, in particular at high solid fractions, where pores have to penetrate the thin liquid channels. For pores spanning over distances larger than the average DAS, the simulations showed that the radius of curvature can vary between two limits, which are given by the size of the narrowest section that the pore needs to pass in order to expand and by the largest sphere that can be fitted in the interdendritic liquid. The pore curvature is therefore a complex non-monotonic function of the DAS, the solid fraction, the hydrogen content and statistical variations of the liquid channel width. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Meidani H.,Ecole Polytechnique Federale de Lausanne | Desbiolles J.-L.,Ecole Polytechnique Federale de Lausanne | Jacot A.,Ecole Polytechnique Federale de Lausanne | Jacot A.,Y-Parc SA | Rappaz M.,Ecole Polytechnique Federale de Lausanne
Acta Materialia | Year: 2012

A three-dimensional (3-D) multiphase-field model has been developed in order to study the formation of a micropore constrained to grow in a solid network (i.e. pinching effect). The model accounts for the pressure difference due to capillarity between liquid and gas, the equilibrium condition at triple (solid-liquid-pore) lines, and the partitioning and diffusion of dissolved gases such as hydrogen. From the predicted 3-D morphology of the pore, entities such as the interfacial shape distribution are plotted and analyzed. It is shown that the mean curvature of the pore-liquid surface, and thus also the pressure inside the pore, is uniform. The results are then compared with analytical pinching models. While predicting a similar trend, analytical models tend to underestimate the pore curvature at high solid fractions. Despite the complex morphology of pores reconstructed using high-resolution X-ray tomography, the present phase-field results suggest that a simple pinching model based on a spherical tip growing in between remaining liquid channels is a fairly good approximation. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Bozukova D.,University of Liège | Pagnoulle C.,Y-Parc SA | Jerome R.,University of Liège | Jerome C.,University of Liège
Materials Science and Engineering R: Reports | Year: 2010

Cataract surgery is the most frequently performed surgical intervention, pursued by replacement of the opacified natural lens by a polymeric intraocular lens (IOL). This paper, based on an exhaustive number of scientific references, provides a brief simplified discussion of the surgical advances for cataract treatment, and is mainly focused on the process of IOL discovery, engineering and development. The performances of the polymer materials, used for the IOLs fabrication are discussed in a comparative way, and their properties, such as handling during surgery, biocompatibility, rate of some post-surgical complications (e.g. Posterior Capsular Opacification) and optical properties, are considered. Special attention is paid on the basic scientific approaches for engineering and modification of the IOL surface and bulk properties. Polymer coating techniques like 'grafting onto' and 'grafting from' are discussed and exemplified by a variety of coating compositions and performances. In another part of the review, modification techniques concerning optimization of the bulk properties of the polymer lens are also discussed and synthetic approaches such as copolymerization and nanocomposite formation are considered. A perspective aspect of this discussion concerns improvement of the performance of the main polymer by the incorporation of in situ formed or preformed nanoparticles. The most attractive perspectives concerning the improvement of the IOL properties by chemical modification approaches are described. © 2010 Elsevier B.V. All rights reserved.

Rooke R.,Y-Parc SA
Biochimica et Biophysica Acta - Molecular Cell Research | Year: 2014

Experimental evidence shows the importance of the immune system in controlling tumor appearance and growth. Immunotherapy is defined as the treatment of a disease by inducing, enhancing or suppressing an immune response. In the context of cancer treatment, it involves breaking tolerance to a cancer-specific self-antigen and/or enhancing the existing anti-tumor immune response, be it specific or not. Part of the complexity in developing such treatment is that cancers are selected to escape adaptive or innate immune responses. These escape mechanisms are numerous and they may cumulate in one cancer. Moreover, different cancers of a same type may present different combinations of escape mechanisms. The limited success of immunotherapeutics in the clinic as stand-alone products may in part be explained by the fact that most of them only activate one facet of the immune response. It is important to identify novel methods to broaden the efficacy of immunotherapeutics. Calcium signaling is central to numerous cellular processes, leading to immune responses, cancer growth and apoptosis induced by cancer treatments. Calcium signaling in cancer therapy and control will be integrated to current cancer immunotherapy approaches. This article is part of a Special Issue entitled: Calcium Signaling in Health and Disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau. © 2014 Elsevier B.V.

The use of the grinding technology in order to obtain smooth and quiet running conditions marked the beginning of a remarkable development leading to rail care which today is indispensable for heavy-duty railway tracks. Despite special use to guarantee low noise levels treatment of the longitudinal profile has become secondary. As a consequence of increased axle loads, higher line speeds and the use of powerful traction units providing optimal interaction of wheel and rail profiles has become a major issue. Cyclic maintenance of rail-heads does not only provide consistently good contact conditions but prevents the development of rolling contact fatigue by regular minor metal removal from the top of the rail surface. This avoids undesired consequences such as rail breaks or premature rail withdrawals. The following article describes the tremendous development rail grinding has achieved during the past 30 years.

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