Murine tumor cell activity on in vitro hemostasis

The procoagulant activity of various murine tumor cells was investigated. This activity is different from tumor to tumor in quality and strength. This parameter must be taken into account in any experiment designed to explore the metastatic spread or to cure tumors, including the use of drugs that modify hemostasis.     

Geometric Applications of the Split Bregman Method: Segmentation and Surface Reconstruction

Variational models for image segmentation have many applications, but can be slow to compute. Recently, globally convex segmentation models have been introduced which are very reliable, but contain TV-regularizers, making them difficult to compute. The previously introduced Split Bregman method is a technique for fast minimization of L1 regularized functionals, and has been applied to denoising and compressed sensing problems. By applying the Split Bregman concept to image segmentation problems, we build fast solvers which can out-perform more conventional schemes, such as duality based methods and graph-cuts. The convex segmentation schemes also substantially outperform conventional level set methods, such as the Chan-Vese level set-based segmentation algorithm. We also consider the related problem of surface reconstruction from unorganized data points, which is used for constructing level set representations in 3 dimensions. The primary purpose of this paper is to examine the effectiveness of “Split Bregman” techniques for solving these problems, and to compare this scheme with more conventional methods.     

Purification of single-walled boron nitride nanotubes and boron nitride cages

Continuous laser vaporization of a BN target under N2 atmosphere is up to now the unique route to single-walled boron nitride nanotubes (BN-SWNTs). Although grams of product can be obtained by this technique, the raw material contains in addition to the BN-SWNTs, different by-products made of boron and nitrogen. Since these materials are undesirable for the studying of the intrinsic properties of the nanotubes, we have undertaken a purification process using chemical and physical methods to separate the different components. We show here that most impurities can be removed by successive cycles of washing, sonication, and centrifugation. Furthermore, the two different types of boron nitride nanostructures i.e., BN-SWNTs and BN-cages can be isolated. Efficiency of the separation was monitored by transmission electron microscopy (TEM) at the different steps of the process. Finally, we envisage the further purification of the nanotubes-enriched fraction by functionalizing the nanotubes in a non covalent manner by specific polymers as for carbon nanotubes and BN multi-walled nanotubes.     

Raman spectroscopy of the polymorphic forms and liquid state of cocoa butter

Raman spectroscopy was used to characterize the polymorphs and liquid state of cocoa butter, with emphasis placed on the evolution of the ester carbonyl stretching region (1800–1700 cm^?1), along with complementary analysis and comparison of the Raman‐active C? C (1200–1000 cm^?1), C?C (1660 cm^?1), C? H (3000–2700 cm^?1) and CH₂ (1500–1250 cm^?1) vibrational modes. Unique Raman signatures were obtained for all cocoa butter polymorphs, with their identity confirmed using DSC and XRD. The ester carbonyl region permitted polymorph discrimination due to differences in the number of modes, their relative frequencies and their full‐widths at half‐maximum. The C? C stretching modes, which provided insight into the trans/gauche content, were polymorph‐independent. C? H stretching generally increased with polymorph stability, indicating the dominance of antisymmetric C? H methylene vibrations as the cocoa butter crystal lattice became more ordered. The change in the intensities of the C? H stretching bands used to probe the order–disorder transition of forms IV, V and VI hinted at pre‐melt structural changes mostly in forms IV and V. Overall, Raman spectroscopy clearly demonstrated that the different functional groups studied could be characterized independently, allowing for the understanding of their role in cocoa butter polymorphism. Practical applications : Fat bloom is the unwanted, uncontrolled re‐crystallization or polymorphic transition of CB form V crystals into form VI normally caused by the migration of lower‐melting fats (e.g. in centre‐filled products) and/or temperature fluctuations during storage. In its mildest form, it appears as an overall dulling of the chocolate surface. In its extreme form, the appearance of the chocolate deteriorates significantly with the development of distinct white patches. Though forms V and VI can be clearly distinguished via XRD, we present evidence that Raman spectral characterization of the ester carbonyl stretching (1800–1700 cm^?1), C? C (1200–1000 cm^?1), C?C (1660 cm^?1), C? H (3000–2700 cm^?1) and CH₂ (1500–1250 cm^?1) vibrational modes yields distinct liquid–solid and polymorph‐dependent differences in CB. From a practical standpoint, the unique signatures associated with forms V and VI offer novel possibilities in the study of fat bloom formation, such as the development of predictive tools.     

Calcium silicate hydrates investigated by solid‐state high resolution H and Si nuclear magnetic resonance

This work focuses on phases formed during cement hydration under high pressure and temperature: portlandite Ca(OH)₂ (CH); hillebrandite Ca₂(SiO₃)(OH)₂ (β‐dicalcium silicate hydrate); calcium silicate hydrate (C-S-H); jaffeite Ca₆(Si₂O₇)(OH)₆ (tricalcium silicate hydrate); α‐C₂SH Ca₂(SiO₃)(OH)₂ (α‐dicalcium silicate hydrate); xonotlite Ca₆(Si₆O₁₇)(OH)₂ and kilchoanite Ca₆(SiO₄)(Si₃O₁₀). Portlandite and hillebrandite were synthesized and characterised by high resolution solid‐state ¹H and ²⁹Si Nuclear Magnetic Resonance. In addition, information from the literature concerning the last five phases was gathered. In certain cases, a schematic 3D‐structure could be determined. These data allow identification of the other phases present in a mixture. Their morphology was also observed by Scanning Electron Microscopy.     

Detailed investigation of geometrical factor for pseudo-MOS transistor technique

The pseudo-MOS transistor technique is useful for quick and accurate characterization of as-fabricated silicon-on-insulator wafers. The sample size and probe-pressure effects on the drain current are revisited. It is demonstrated that the geometrical factor is significantly affected by the probe-to-edge distance and probe pressure. The correct geometrical factor, reflecting silicon island size, and probe pressure effects, is extracted from systematic experimental results and used to determine the actual carrier mobility.     

Possible influence of the Schottky contacts on the characteristics of ultrathin SOI pseudo-MOS transistors

The paper describes the impact of pseudo-MOS technique on threshold and flatband voltages, and why the threshold and flatband voltages depend on silicon-on-insulator (SOI) layer thickness. Our measurements and simulations suggest that the band-offset-induced depletion beneath the source contact obstructs the local formation of the inversion layer at the SOI/buried oxide interface; this effect becomes significant when the SOI layer thickness is reduced. The SOI layer thickness dependence of flatband voltage is analyzed in a similar manner. The temperature dependence of threshold and flatband voltages is also addressed.     

Functionalization of polymethylhydrosiloxane gels with an allyl ureido benzocrown ether derivative: Complexation properties

Crosslinked polymethylhydrosiloxane (PMHS) thin films prepared by sol–gel polycondensation have been functionalized by Pt‐catalyzed hydrosilylation of SiH groups with an allyl ureido crown ether precursor. To this purpose, both 4′‐allylurea‐benzo‐15‐crown‐5 ( 1 ) and 1‐allyl‐3‐propyl‐urea ( 2 ) were synthesized and characterized. We have shown that competitive side‐reactions occurred following hydrosilylation due to the hydrolysis of part of the SiH groups resulting in the formation of new crosslinks Si(CH₃)O_3/2 as shown by solid‐state ²⁹Si‐NMR. This is explained by the deactivation of the Pt catalyst toward hydrosilylation by amide groups. For thin films (～ 1 μm) prepared on silicon wafers, a quantitative method based on FT‐IR transmission spectroscopy was used to measure the crosslinking density of the network, and the percentage of functionalization (SiC %) following hydrosilylation. The results are discussed in relation to the mesh size of the network, and the diffusion of alkenes and water molecules within lightly crosslinked PMHS gels obtained by varying the amount of triethoxysilane crosslinker (mol %) from 15 to 1%. The self‐organization properties of ureido groups by H‐bonding were studied by FT‐IR for the functionalized thin films. The complexation properties of the crown ether 1 ‐functionalized thin films were evidenced by using FT‐IR following diffusion‐reactions of NaSCN and KSCN salts in CHCl₃ : MeOH solvent mixtures within thin films. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Scale space analysis and active contours for omnidirectional images.

A new generation of optical devices that generate images covering a larger part of the field of view than conventional cameras, namely catadioptric cameras, is slowly emerging. These omnidirectional images will most probably deeply impact computer vision in the forthcoming years, provided that the necessary algorithmic background stands strong. In this paper, we propose a general framework that helps define various computer vision primitives. We show that geometry, which plays a central role in the formation of omnidirectional images, must be carefully taken into account while performing such simple tasks as smoothing or edge detection. Partial differential equations (PDEs) offer a very versatile tool that is well suited to cope with geometrical constraints. We derive new energy functionals and PDEs for segmenting images obtained from catadioptric cameras and show that they can be implemented robustly using classical finite difference schemes. Various experimental results illustrate the potential of these new methods on both synthetic and natural images.     

Representing diffusion MRI in 5-D simplifies regularization and segmentation of white matter tracts

We present a new five-dimensional (5-D) space representation of diffusion magnetic resonance imaging (dMRI) of high angular resolution. This 5-D space is basically a non-Euclidean space of position and orientation in which crossing fiber tracts can be clearly disentangled, that cannot be separated in three-dimensional position space. This new representation provides many possibilities for processing and analysis since classical methods for scalar images can be extended to higher dimensions even if the spaces are not Euclidean. In this paper, we show examples of how regularization and segmentation of dMRI is simplified with this new representation. The regularization is used with the purpose of denoising and but also to facilitate the segmentation task by using several scales, each scale representing a different level of resolution. We implement in five dimensions the Chan-Vese method combined with active contours without edges for the segmentation and the total variation functional for the regularization. The purpose of this paper is to explore the possibility of segmenting white matter structures directly as entirely separated bundles in this 5-D space. We will present results from a synthetic model and results on real data of a human brain acquired with diffusion spectrum magnetic resonance imaging (MRI), one of the dMRI of high angular resolution available. These results will lead us to the conclusion that this new high-dimensional representation indeed simplifies the problem of segmentation and regularization.