Kill Line Model Cross Flow Inline Coupled Vortex-Induced Vibration

Currents and waves cause flow-structure interaction problems in systems installed in the ocean. Particularly for bluff bodies, vortices form in the body wake, which can cause strong structural vibrations (Vortex-Induced Vibrations, VIV). The magnitude and frequency content of VIV is determined by the shape, material properties, and size of the bluff body, and the nature and velocity of the oncoming flow. Riser systems are extensively used in the ocean to drill for oil wells, or produce oil and gas from the bottom of the ocean. Risers of ten consist of a central pipe, surrounded by several smaller cylinders, including the kill and choke lines. We present a series of experiments involving forced in-line and cross flow motions of short rigid sections of a riser containing 6 symmetrically arranged kill and choke lines. The experiments were carried out at the MIT Towing Tank. We present a systematic database of the hydrodynamic coefficients, consisting of the forces in phase with velocity and the added mass coefficients that are also suitable to be used with semi-empirical VIV predicting codes

Stochastic homogenization of the laser intensity to improve the irradiation uniformity of capsules directly driven by thousands laser beams

Illumination uniformity of a spherical capsule directly driven by laser beams has been assessed numerically. Laser facilities characterized by ND = 12, 20, 24, 32, 48 and 60 directions of irradiation with associated a single laser beam or a bundle of NB laser beams have been considered. The laser beam intensity profile is assumed super-Gaussian and the calculations take into account beam imperfections as power imbalance and pointing errors. The optimum laser intensity profile, which minimizes the root-mean-square deviation of the capsule illumination, depends on the values of the beam imperfections. Assuming that the NB beams are statistically independents is found that they provide a stochastic homogenization of the laser intensity associated to the whole bundle, reducing the errors associated to the whole bundle by the factor  , which in turn improves the illumination uniformity of the capsule. Moreover, it is found that the uniformity of the irradiation is almost the same for all facilities and only depends on the total number of laser beams Ntot = ND × NB

Is a persistent global bias necessary for the establishment of planar cell polarity?

Planar cell polarity (PCP)–the coordinated polarisation of a whole field of cells within the plane of a tissue–relies on the interaction of three modules: a global module that couples individual cellular polarity to the tissue axis, a local module that aligns the axis of polarisation of neighbouring cells, and a readout module that directs the correct outgrowth of PCP-regulated structures such as hairs and bristles. While much is known about the molecular components that are required for PCP, the functional details of–and interactions between–the modules remain unclear. In this work, we perform a mathematical and computational analysis of two previously proposed computational models of the local module (Amonlirdviman et al., Science, 307, 2005; Le Garrec et al., Dev. Dyn., 235, 2006). Both models can reproduce wild-type and mutant phenotypes of PCP observed in the Drosophila wing under the assumption that a tissue-wide polarity cue from the global module persists throughout the development of PCP. We demonstrate that both models can also generate tissue-level PCP when provided with only a transient initial polarity cue. However, in these models such transient cues are not sufficient to ensure robustness of the resulting cellular polarisation

Photocytotoxicity of mTHPC (Temoporfin) Loaded Polymeric Micelles Mediated by Lipase Catalyzed Degradation

Purpose. To study the in vitro photocytotoxicity and cellular uptake of biodegradable polymeric micelles loaded with the photosensitizer mTHPC, including the effect of lipase-catalyzed micelle degradation. Methods. Micelles of mPEG750-b-oligo(ɛ-caprolactone)5 (mPEG750-b-OCL5) with a hydroxyl (OH), benzoyl (Bz) or naphthoyl (Np) end group were formed and loaded with mTHPC by the film hydration method. The cellular uptake of the loaded micelles, and their photocytotoxicity on human neck squamous carcinoma cells in the absence and presence of lipase were compared with free and liposomal mTHPC (Fospeg ®). Results. Micelles composed of mPEG750-b-OCL5 with benzoyl and naphtoyl end groups had the highest loading capacity up to 30 % (w/w), likely due to π–π interactions between the aromatic end group and the photosensitizer. MTHPC-loaded benzoylated micelles (0.5 mg/mL polymer) did not display photocytotoxicity or any mTHPC-uptake by the cells, in contrast to free and liposomal mTHPC. After dilution of the micelles below the critical aggregation concentration (CAC), or after micelle degradation by lipase, photocytotoxicity and cellular uptake of mTHPC were restored. Conclusion. The high loading capacity of the micelles, the high stability of mTHPC-loaded micelles above the CAC, and the lipase-induced release of the photosensitizer makes these micelles very promising carriers for photodynamic therapy in vivo. KEY WORDS: drug release; enzymatic degradation; meta-tetra(hydroxyphenyl)chlorin (mTHPC); photodynamic therapy (PDT); polymeric micelles

Self-Assembled Polymeric Micellar Nanoparticles as Nanocarriers for Poorly Soluble Anticancer Drug Ethaselen

A series of monomethoxy poly(ethylene glycol)-poly(lactide) (mPEG-PLA) diblock copolymers were synthesized, and mPEG-PLA micelle was fabricated and used as a nanocarrier for solubilization and delivery of a promising anticancer drug ethaselen. Ethaselen was efficiently encapsulated into the micelles by the dialysis method, and the solubility of ethaselen in water was remarkably increased up to 82 μg/mL before freeze-drying. The mean diameter of ethaselen-loaded micelles ranged from 51 to 98 nm with a narrow size distribution and depended on the length of PLA block. In vitro hemolysis study indicated that mPEG-PLA copolymers and ethaselen-loaded polymeric micelles had no hemolytic effect on the erythrocyte. The enhanced antitumor efficacy and reduced toxic effect of ethaselen-loaded polymeric micelle when compared with ethaselen-HP-β-CD inclusion were observed at the same dose in H22human liver cancer cell bearing mouse models. These suggested that mPEG-PLA polymeric micelle nanoparticles had great potential as nanocarriers for effective solubilization of poorly soluble ethaselen and further reducing side effects and toxicities of the drug

Genetic Control of Organ Shape and Tissue Polarity

A combination of experimental analysis and mathematical modelling shows how the genetic control of tissue polarity plays a fundamental role in the development and evolution of form

Large-Scale Clonal Analysis Reveals Unexpected Complexity in Surface Ectoderm Morphogenesis

Background: Understanding the series of morphogenetic processes that underlie the making of embryo structures is a highly topical issue in developmental biology, essential for interpreting the massive molecular data currently available. In mouse embryo, long-term in vivo analysis of cell behaviours and movements is difficult because of the development in utero and the impossibility of long-term culture. Methodology/Principal Findings: We improved and combined two genetic methods of clonal analysis that together make practicable large-scale production of labelled clones. Using these methods we performed a clonal analysis of surface ectoderm (SE), a poorly understood structure, for a period that includes gastrulation and the establishment of the body plan. We show that SE formation starts with the definition at early gastrulation of a pool of founder cells that is already dorso-ventrally organized. This pool is then regionalized antero-posteriorly into three pools giving rise to head, trunk and tail. Each pool uses its own combination of cell rearrangements and mode of proliferation for elongation, despite a common clonal strategy that consists in disposing along the antero-posterior axis precursors of dorso-ventrally-oriented stripes of cells. Conclusions/Significance: We propose that these series of morphogenetic processes are organized temporally and spatially in a posterior zone of the embryo crucial for elongation. The variety of cell behaviours used by SE precursor cells indicates that these precursors are not equivalent, regardless of a common clonal origin and a common clonal strategy. Anothe

Propagation of LIL/LMJ beams under the interaction with contamination particles and component surface defects

This paper presents recent studies of the propagation of high-power laser beams like Laser Integration Line (LIL) and Laser MegaJoule (LMJ) beams, when interactions occur with environmental pollution particles and component defects. The studies are mainly achieved with the CEA-DAM MIRÓ beam propagation code. The highest intensifications in the downstream propagation are obtained for phase objects like dielectric particles, scratches or laser damage rather than for amplitude objects like metallic particles. Dramatic amplification of Kerr nonlinear effect leading to beam self-focusing inside the component is predicted depending on the particle size. The effect of statistical distributions of end-of-line phase defects on the LIL/LMJ 0.351-$\mu$m-wavelength focal spot intensity and size is quantified

X-Ray Studies of Combustion Generated Nanostructures

5th Conference of the Saudi-Physical-Society (SPS), Abha, SAUDI ARABIA, OCT 25-27, 2010International audienceSmall Angle X-ray Scattering (SAXS) has been used to measure in-situ the size, morphology and concentration of soot particles in an ethylene diffusion flame. The results obtained are compared to those taken using other experimental techniques

Synchrotron Radiation Studies of Additives in Combustion, II: Soot Agglomerate Microstructure Change by Alkali and Alkaline-Earth Metal Addition to a Partially Premixed Flame

International audienceSmall-angle X-ray scattering (SAXS) has been used in a comparative study to characterize soot particle formation in a partially premixed ethylene−air flame into which plain water, and 0.1 mol/L solutions of potassium chloride, cesium chloride, barium chloride, and calcium chloride were aspirated. The plain water results are assumed to be the reference in this study. On the basis of previous findings, a two-level universal fitting function for the scattering intensity I(q), 0.04 nm−1 < q < 0.5 nm−1, is used to retrieve the size and concentration of both primary particles, which are the subunits of relatively large (100 nm) fractal aggregates, and smaller subprimary particles, which aggregate in turn to form primaries. It is found that CsCl addition produces 40% smaller primary particles at larger residence times, compared to plain water addition. CaCl2, BaCl2, and KCl addition have almost no effect on primary and subprimary sizes. Cesium chloride addition produces a dramatic reduction of the subprimary particle dimension, up to a factor of 2.2, while the concentration of primaries and subprimaries is increased by factors of up to 5 and 2, respectively, with respect to plain water. The contribution to the soot volume fraction (fv) from primary and subprimary particles is separately estimated for all the additives, with respect to the standard plain water addition. At larger residence times, CsCl addition leads to a reduction of the fv contribution from primaries, with larger rates compared to KCl. On the other hand, the effect of suppression by CsCl at smaller heights can be weaker than pure water, contrary to KCl, which is a better fv suppressor than water at all heights, even if a smaller rate than that for CsCl is in operation. The effect of CsCl and KCl is the same for the subprimary fv contribution. BaCl2 has the effect of yielding a primary fv contribution, which is a factor of 2 smaller than that for plain water, almost independently of the height in the flame and, moreover, it yields a large decrease (up to a factor of 4 at a height above the burner (HAB) of 28 mm) in the subprimary fv contribution, compared to plain water. CaCl2 addition has a negligible effect on both the primary and subprimary fv contribution, with respect to water