Global behaviour of a composite stiffened panel in buckling. Part 1: Numerical modelling

The present study analyses an aircraft composite fuselage structure manufactured by the Liquid Resin Infusion (LRI) process and subjected to a compressive load. LRI is based on the moulding of high performance composite parts by infusing liquid resin on dry fibres instead of prepreg fabrics or Resin Transfer Moulding (RTM). Actual industrial projects face composite integrated structure issues as a number of structures (stiffeners, …) are more and more integrated onto the skins of aircraft fuselage. A representative panel of a composite fuselage to be tested in buckling is studied numerically.     

Particle-SfT: A Provably-Convergent,Fast Shape-from-Template Algorithm

The Shape-from-Template (SfT) problem is to recover the 3D shape of a deformable object from a single image, given a 3D template and a deformation constraint. We propose Particle-SfT, a new SfT algorithm which handles isometric and non-isometric deformations. We build Particle-SfT upon a particle system guided by deformation and reprojection constraint projections. Reconstruction is achieved by evolving particles to a globally attractive equilibrium, while taking observable external forces such as gravity into account, if any. Particle-SfT may be used to refine an existing initial shape. However, in practice we simply use the template as initial guess. This is because, as opposed to the existing refining methods, Particle-SfT has an extremely wide convergence basin. Particle-SfT is also faster than the existing refining methods. This is because it moves pieces of the shape’s mesh independently to achieve larger step size by optimal constraint projection. We proved its convergence to a fixed-point. We experimented it with synthetic and real data. It has the same accuracy as the best performing isometric method and consistently outperforms all existing elastic methods in almost all cases, while being much faster.     

A randomised controlled trial of a low-molecular-weight heparin (Enoxaparin) to prevent deep-vein thrombosis in patients undergoing vascular surgery

The incidence of postoperative deep vein thrombosis (PDVT) after aortic surgery and lower limb revascularisation has not been assessed by a large prospective study. In a prospective randomised trial the effect of a low-molecular-weight heparin fragment, Enoxaparin (ENX) 4200 anti factor Xa IU once daily was compared to that of unfractionated heparin (UFH) 7500 IU twice daily. Two hundred and thirty-three consecutive patients were classified into three groups, aortic or aortoiliac and aneurysmectomy (n = 75), aorto-femoral bypass for atherosclerotic disease (n = 71), and femoropopliteal or femorodistal bypass (n = 87). Patients were analysed for development of deep vein thrombosis by Duplex scanning and, if positive, by venography between the seventh and tenth postoperative day. PDVT was present in 10 patients in the ENX group and in four patients in the UFH group (8.2 and 3.6% respectively, NS). The incidence of PDVT was 8% after aortic or aortoiliac aneurysmectomy, 7% after aortofemoral revascularisation, and 3.4% after femoropopliteal or femorodistal bypass. The overall incidence of PDVT after aortic surgery was 7.5% (95% CI 5.4-9.7). There was no pulmonary embolism. Intra-operative blood loss and postoperative bleeding events did not differ significantly between the ENX and UFH groups. After 1 month follow-up, no clinical event or death could be related to PDVT or pulmonary embolism. In conclusion, in vascular surgery ENX is as safe and effective in the prevention of PDVT as is UFH.     

The transfer of metallic contamination via contact between solid objects

The transfer of metallic contamination via solid contact is an almost non documented topic in the literature when compared to the spread through liquids which is has been intensively investigated for cleaning studies.This paper presents the transfer mechanisms of metallic aggregates from substrate to substrate though contact with tools used during wafer processing. In addition we propose models which agree with the experimental observations. The influence of several parameters on the transfer coefficients has been investigated, including the type of contamination (deposited films, particles…), the size or shape of the particle, the composition of the particle (metallic or dielectric), the substrate and the roughness and flatness of the plates used to hold the wafers during processing as well as the substrate surface composition (bare Si, oxidized…).The transfer of metals via the contact between solid objects only occurs from particular mechanisms. Not considering electrical forces, the first order parameter on the transfer is the particle size. Global transfer by contact occurs mainly in the 0.5-5 μm range and can be as high as 10%. For the second order, the parameters mentioned previously can affect the transfer of the particles, for example, an increase of the particle roughness induces an increase of the separation distance between particle and substrate which consequently decreases the Van der Waals interactions.     

Hydraulic anisotropy of homogeneous soils and rocks: influence of the densification process

Many values of the ratio k_max/k_min are available for clays and rocks which can be cut for tests in different directions. In comparison, few reliable results are available for non-cohesive materials. The hydraulic anisotropy ratios of homogeneous clays, rocks and granular soils appear to be very similar. In particular, k_max/k_min seems to be lower than 4, which confirms that this ratio has an upper limit related to the shape of particles, their arrangement, or the directional tortuosity within the pore space. In the bedding plane of sedimentary rocks, the ratio k_b.max/k_b.min is usually lower than 1.5, thus these rocks are nearly isotropic in their bedding plane. In granular soils, the k_h/k_v, contrary to common opinion, is not always higher than 1. Experimental values for sands and gravels are in the 0.75 to 4.1 range. The influence of densification on hydraulic anisotropy is found to be similar for a sand and a clay, and probably for any soil having settled in still water and influenced subsequently only by gravity. The hydraulic anisotropy of sandstone is found to be in continuity with that of sand, and it increases with densification.     

Antineoplastic agents. 397: Isolation and structure of sesterstatins 4 and 5 from Hyrtios erecta (the Republic of Maldives)

The wide ranging marine sponge Hyrtios erecta is the source of the spongistatins, a new class of macrocyclic lactone antineoplastic agents. Continuation of a detailed investigation of cancer cell growth inhibitory (P388 lymphocytic leukemia) fractions (trace) from H. erecta has revealed the presence (10(-5) to 10(-7)% yield) of cytotoxic pentacyclic sesterterpenes. Employing P388 leukemia and human tumor cell line-guided bioassay techniques, two new moderate inhibitors of cancer cells were isolated and named sesterstatins 4 (1a, P388 ED50 4.9 micrograms/mL) and 5 (1b, DU-145 prostate GI50 1.9 micrograms/mL). Similar to other sesterterpenes, sesterstatin 5 inhibited growth of a Gram-positive bacterium. High field (500 MHz) 2-D NMR techniques were primarily employed for initial structural assignments, and structural assignments were confirmed by X-ray crystal structure determination of sesterstatin 4 (1a) and 5 (1b).     

A study of spatial parameters encoded during exploration in hamsters.

In two experiments the exploratory reactions of hamsters to various rearrangements of familiar objects were examined. During two sessions, the subjects were allowed to explore a circular, open field containing four different objects. During a third test session, one or several objects were displaced, changing the shape and/or the size of the area defined by the object set. Significant reexploration was found when the change brought about during the test session affected the geometrical relations between the objects or when an object was removed. In contrast, changes that did not modify the geometrical configuration of the arrangement of the objects, but only modified the distance of one object to another, did not elicit any reexploration. Additionally, it was found that selective reexploration of the actually displaced objects occurred only when the change removed this object a certain distance from the others. These results are discussed in terms of stimulus complexity and more generally with regard to the spatial parameters that are selected, processed, and stored during exploration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Further clinical evaluations elicited by functional biological investigations in childhood autism

Data on the protective role of antioxidants in models of atherosclerosis are only partially confirmed in man. Observational and epidemiological data, as well as randomized trials, provide no clear cut indications, because of positive and disappointing results on the use of antioxidants in cardiovascular protection. Despite the lack of a general consensus, recent data reinforce the concept that the regular intake of antioxidants present in food limits the progression of atherosclerosis. When it is possible to monitor the efficacy of any antioxidant therapy with validated markers of oxidation, the potential influence of vitamins and antioxidants on coronary artery disease may eventually be resolved.     

Investigation on the properties of linear PLA-poloxamer and star PLA-poloxamine copolymers for temporary biomedical applications

The objective of this work was to develop and study new biodegradable thermoplastics with improved mechanical properties for potential use as temporary implantable biomaterials. Linear poloxamer and star-shaped poloxamine have been used as macroinitiators for the ring-opening polymerization (ROP) of lactide to yield high molecular weight PLA-based thermoplastic block copolymers. The influence of the nature of the macroinitiator, PLA crystallinity and initial molecular weight on the copolymers properties was investigated by performing a 7-week degradation test in PBS. The evaluation of water uptakes and molecular weights during the degradation pointed out an early hydrolytic degradation of the 100-kg?mol^? 1 copolymers compared to the 200-kg?mol^? 1 ones (molecular weight decrease of ca. 40% and 20%, respectively). A dramatic loss of tensile mechanical properties was also observed for the 100-kg?mol^? 1 copolymers, whereas the 200-kg?mol^? 1 copolymers showed stable or even slightly improved properties with Young's moduli around 500 MPa and yield strains around 3% to 4%. Finally, the cytocompatibility of the more stable 200 kg?mol^? 1 copolymers was confirmed by murine mesenchymal stem cells (MSCs) culture.