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Gotowa bibliografia na temat „Colloidal Chains”

Autor: Grafiati

Data publikacji: 6 września 2023

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Artykuły w czasopismach na temat "Colloidal Chains"

Marschelke, Claudia, Olga Diring i Alla Synytska. "Reconfigurable assembly of charged polymer-modified Janus and non-Janus particles: from half-raspberries to colloidal clusters and chains". Nanoscale Advances 1, nr 9 (2019): 3715–26. http://dx.doi.org/10.1039/c9na00522f.

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pH-triggered, reconfigurable assembly of binary mixtures of hybrid hairy Janus and non-Janus colloids to half-raspberry-like constructs, colloidal clusters and colloidal chains depending on particle size ratio and numerical ratio.

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Liu, Bin, Etienne Duguet i Serge Ravaine. "Solvent-induced assembly of mono- and divalent silica nanoparticles". Beilstein Journal of Nanotechnology 14 (6.01.2023): 52–60. http://dx.doi.org/10.3762/bjnano.14.6.

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Particles with attractive patches are appealing candidates to be used as building units to fabricate novel colloidal architectures by self-assembly. Here, we report the synthesis of one-patch silica nanoparticles, which consist of silica half-spheres whose concave face carries in its center a polymeric patch made of grafted polystyrene chains. The multistage synthesis allows for a fine control of the patch-to-particle size ratio from 0.23 to 0.57. The assembly of the patchy nanoparticles can be triggered by reducing the solvent quality for the polystyrene chains. Dimers or trimers can be obtained by tuning the patch-to-particle size ratio. When mixed with two-patch nanoparticles, one-patch nanoparticles control the length of the resulting chains by behaving as colloidal chain stoppers. The present strategy allows for future elaboration of novel colloidal structures by controlled assembly of nanoparticles.

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METAYER, C., E. COQUELLE, V. A. STERLIGOV, A. MEUNIER, G. BOSSIS i J. PERSELLO. "IMPORTANCE OF CONTROLLING INTERPARTICLE GAPS FOR NOVEL MATERIAL PROPERTIES". International Journal of Modern Physics B 19, nr 07n09 (10.04.2005): 1290–96. http://dx.doi.org/10.1142/s0217979205030207.

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Measurement of average interparticle gap in chains of colloidal particles is realized by means of light scattering in silica suspensions or dynamic mechanical analysis in MR elastomers. For a silica volume fraction of 10% we find that the mean distance between particles inside chains drop off sharply with the increase of field; this behavior is attributed to the presence of a long range ionic repulsive force. We show that this experiment allows to obtain information about interparticle forces between colloidal particles. On the other hand the transmitted light is very sensitive to the size of the particles in the chain and to the gap between particles. In an other domain, namely elastomers containing chains of magnetic particles, the magnetostriction is also found to be determined by the interparticle gap.

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HIMMI, MUSTAPHA, i LAILA MOHAMMADI. "EXTENSIVE STUDY OF INTERACTION FORCE BETWEEN SPHERICAL COLLOIDS AND STAR POLYMERS". International Journal of Modern Physics B 26, nr 17 (21.06.2012): 1250105. http://dx.doi.org/10.1142/s0217979212501056.

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We consider a system consisting of very small colloidal particles clothed each by f end-grafted flexible polymer chains we regarded as star polymers, and hard spherical colloidal particles in a good solvent. Our main objective is to determine the expression of the interaction force between a spherical colloid and a star polymer as a function of distance between them. We limit ourselves to the case where the star polymer is smaller than the colloid. In the first part, the system is dissolved in a melt of short linear chains of polymerization degree P<N, where N denotes the polymerization degree of grafted chains. To compute the expected force, we consider two regimes: (1) high-grafting density [Formula: see text] and (2) small-grafting density (f < f*). For (f > f*), we show that the expression of the expected force coincides exactly with that of the case of a small molecular weight solvent. For (f < f*), we show that there is a change in behavior. In the second part, we assume that the lengths of the f grafted chains were randomly distributed and there is talk of a polydisperse star polymer. We show that the computation of the expected force depends on the relative values of the polymerization degree of longest grafted chain, N, when it is compared to the typical one Nc ~ f1/(α-1). Here α is the polydispersity exponent. We distinguish two regimes depending on whether N < Nc or N > Nc. For the regime with N < Nc, and comparing the expression of the force obtained for the monodisperse case, we can say that the polydispersity of grafted chains induce a drastic change of the force expression. For the regime with N > Nc, we found the existence of two distance-ranges. For small distances, the effective force expression is identical to that relative to the above case (N < Nc). But for high distances, the effective force expression is similar to the monodisperse case.

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Kim, Jeong-Hee, Won Jong Kwon i Byeong-Hyeok Sohn. "Supracolloidal polymer chains of diblock copolymer micelles". Chemical Communications 51, nr 16 (2015): 3324–27. http://dx.doi.org/10.1039/c4cc09518a.

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Yang, Tao, Brennan Sprinkle, Yang Guo, Jun Qian, Daoben Hua, Aleksandar Donev, David W. M. Marr i Ning Wu. "Reconfigurable microbots folded from simple colloidal chains". Proceedings of the National Academy of Sciences 117, nr 31 (17.07.2020): 18186–93. http://dx.doi.org/10.1073/pnas.2007255117.

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To overcome the reversible nature of low-Reynolds-number flow, a variety of biomimetic microrobotic propulsion schemes and devices capable of rapid transport have been developed. However, these approaches have been typically optimized for a specific function or environment and do not have the flexibility that many real organisms exhibit to thrive in complex microenvironments. Here, inspired by adaptable microbes and using a combination of experiment and simulation, we demonstrate that one-dimensional colloidal chains can fold into geometrically complex morphologies, including helices, plectonemes, lassos, and coils, and translate via multiple mechanisms that can be varied with applied magnetic field. With chains of multiblock asymmetry, the propulsion mode can be switched from bulk to surface-enabled, mimicking the swimming of microorganisms such as flagella-rotating bacteria and tail-whipping sperm and the surface-enabled motion of arching and stretching inchworms and sidewinding snakes. We also demonstrate that reconfigurability enables navigation through three-dimensional and narrow channels simulating capillary blood vessels. Our results show that flexible microdevices based on simple chains can transform both shape and motility under varying magnetic fields, a capability we expect will be particularly beneficial in complex in vivo microenvironments.

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Yang, Tao, David W. M. Marr i Ning Wu. "Superparamagnetic colloidal chains prepared via Michael-addition". Colloids and Surfaces A: Physicochemical and Engineering Aspects 540 (marzec 2018): 23–28. http://dx.doi.org/10.1016/j.colsurfa.2017.12.044.

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Zhang, H., i M. Widom. "Field-induced forces in colloidal particle chains". Physical Review E 51, nr 3 (1.03.1995): 2099–103. http://dx.doi.org/10.1103/physreve.51.2099.

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GRÜNZEL, MAREIKE. "SIMULATION OF COLLOIDAL CHAIN MOVEMENTS UNDER A MAGNETIC FIELD". International Journal of Modern Physics C 16, nr 07 (lipiec 2005): 1091–95. http://dx.doi.org/10.1142/s0129183105007753.

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Short colloidal chains are simulated by the slithering-snake-algorithm on a simple cubic lattice. The dipole character of the colloidal particles leads to a long range dipole–dipole interaction. The solvent is simulated by the nearest neighbor Ising model. The aligning of the dipoles under a magnetic field gives rise to the chains to align on their part with the field direction.

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Semenov, A. N., i A. A. Shvets. "Theory of colloid depletion stabilization by unattached and adsorbed polymers". Soft Matter 11, nr 45 (2015): 8863–78. http://dx.doi.org/10.1039/c5sm01365h.

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Rozprawy doktorskie na temat "Colloidal Chains"

SHAY, JENNIFER SUSAN. "AQUEOUS COLLOIDAL DISPERSIONS WITH GRAFTEDPOLY(ETHYLENE OXIDE) CHAINS: SYNTHESIS, MICROSTRUCTURE,AND RHEOLOGY". NCSU, 1999. http://www.lib.ncsu.edu/theses/available/etd-19991028-144944.

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SHAY, JENNIFER SUSAN. Aqueous Colloidal Dispersions with GraftedPoly(Ethylene Oxide) Chains: Synthesis, Microstructure, and Rheology. (Underthe direction of Saad A. Khan.)

Water-based coatings are an environmentally benign alternative to thesolvent-based systems traditionally used in industry. Water-based systems containcolloidal particles dispersed in an aqueous medium and are typically stabilizedthrough electrostatic means. Widespread acceptance of water-based coatings hasbeen hindered by their low solids content, which leads to slow drying rates andinconsistent quality. This study focuses on developing a model coating systembased upon a novel poly(ethylene oxide) (PEO)-based macromer that can be graftedto the surfaces of the colloidal particles, stabilizing the particles against flocculationand allowing the coating to be processed at a high solids content. The initial phaseof this study involves the synthesis of colloidal polystyrene (PS) latex dispersionssterically stabilized with these PEO-based macromers, and the identification of theeffects of synthesis parameters on molecular and structural properties. Electronmicroscopy reveals the spherical, submicron morphology of the latex particles, andproton nuclear magnetic resonance data confirms a direct correlation between theamount of macromer in the reaction feed and the amount grafted to the PS particles.In the second phase of the research, rheological techniques are used to investigateflow behavior and interparticle interactions for latex dispersions with differentamounts of grafted macromer. Dynamic rheological experiments reveal that, at high macromer concentrations, the PEO surface layer effectively shields theattractive interactions between the core PS particles that lead to flocculation.However, at low macromer concentrations, strong interactions are seen even at lowparticle weight fractions, indicating the presence of a flocculated system. Steadyshear rheological evaluations show that the latex systems possess suitable flowbehavior for coating applications, even at high particle contents. Steady shear data,in conjunction with the Krieger-Dougherty model, confirm that the stabilizing layerthickness decreases as particle concentration increases, indicating a compressiblesystem. In addition, the relationship between the strength of interparticleinteractions and PEO graft density is gauged by a power law model relating theelastic modulus to particle concentration. The third phase of the study examines theeffects of temperature on interparticle interactions and dispersion stability.Dynamic rheological experiments reveal a sol-gel transition as temperature isincreased, with the transition temperature being dependent on the PEO graftdensity. Dynamic light scattering measurements show a change in apparent particlesize at the sol-gel transition. The transition is postulated to be due to the collapseof the PEO chains as temperature is increased (i.e., solvent quality is decreased),which allows the attractive forces between the PS particles to dominate the stericrepulsion provided by the stabilizing layer. The PEO chain collapse is attributed tothe disruption of the structured orientation of the hydrogen-bonded water moleculesthat surround the PEO.

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Shay, Jennifer Susan. "Aqueous colloidal dispersions with grafted poly(ethylene oxide) chains synthesis, microstructure, and rheology /". Raleigh, NC : North Carolina State University, 1999. http://www.lib.ncsu.edu/etd/public/etd-441142989932711/etd.pdf.

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Clark, Anthony. "Properties of Effective Pair Potentials that Map Polymer Melts onto Liquids of Soft Colloid Chains". Thesis, University of Oregon, 2013. http://hdl.handle.net/1794/13005.

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The ability to accurately represent polymer melts at various levels of coarse graining is of great interest because of the wide range of time and length scales over which relevant process take place. Schemes for developing effective interaction potentials for coarse-grained representations that incorporate microscopic level system information are generally numerical and thus suffer from issues of transferability because they are state dependent and must be recalculated for different system and thermodynamic parameters. Numerically derived potentials are also known to suffer from representability problems, in that they may preserve structural correlations in the coarse-grained representation but many often fail to preserve thermodynamic averages of the coarse-grained representation. In this dissertation, analytical forms of the structural correlations and effective pair potentials for a family of highly coarse-grained representations of polymer melts are derived. It is shown that these effective potentials, when used in mesoscale simulations of the coarse-grained representation, generate consistent equilibrium structure and thermodynamic averages with low level representations and therefore with physical systems. Furthermore, analysis of the effective pair potential forms shows that a small long range tail feature that scales beyond the physical range of the polymer as the fourth root of the number of monomers making up the coarse-grained unit dominates thermodynamic averages at high levels of coarse graining. Because structural correlations are extremely insensitive to this feature, it can be shown that effective interaction potentials derived from optimization of structural correlations would require unrealistically high precision measurements of structural correlations to obtain thermodynamically consistent potentials, explaining the problems of numerical coarse-graining schemes. This dissertation includes previously published and unpublished co-authored material.

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Wemmer, Susan. "Expression and engineering of recombinant antibodies against a heat-shock protein of Mycobacterium bovis". Diss., University of Pretoria, 2008. http://hdl.handle.net/2263/28886.

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In the medical and veterinary diagnostic fields there is an ongoing need for stable and specific antibodies. There is also a requirement for simple, robust and cost-effective diagnostic assays to be used in the developing world. Recombinant antibodies from phage displayed libraries are economical to produce and can often be engineered to improve affinity, avidity and stability. While recombinant antibody fragments are useful in immunoassays, they are not strictly comparable to normal immunoglobulins and may under-perform in certain assays. Converting monovalent single-chain antibody fragments (scFvs) to bivalent immunoglobulin-like formats could conceivably provide a more suitable molecular scaffold for use in immunoassays. Two scFvs that recognised the 65 kDa heat-shock protein (HSP65) of Mycobacterium bovis were used in this study. They were originally derived from the Nkuku® repertoire, a phage displayed antibody library based on the immune repertoire of the chicken, Gallus gallus. The genes coding for these scFvs were subcloned in expression vectors containing chicken IgY constant-heavy domains, to create bivalent constructs which were designated ‘gallibodies’. Expression of these constructs was attempted in three heterologous systems. While they were successfully produced in adherent mammalian cell cultures, the growth requirements of these cultures complicated subsequent purification. Bacteria and yeasts were investigated as alternative expression systems, but antibodies were not produced in either system. The gallibodies were compared to their monovalent scFv counterparts for stability as well as their applicability in ELISAs and gold-conjugated immunochromatographic lateral-flow assays. As gallibodies, both retained their functionality after exposure to different conditions and they were capable of immunocapture in ELISA. This was in contrast to their performance as scFvs. Furthermore, these antibody-like molecules could be stably conjugated to colloidal gold and used in lateral flow tests where positive and specific signals were obtained. This confirmed that recombinant single-chain monomeric antibody fragments could be reconstituted as bivalent immunoglobulin-like molecules and that they are a potentially useful platform for developing practical, robust immunodiagnostic reagents. It appeared from these experiments that the antibodies could act as a pair in which one captures, and the other detects HSP65. To find out whether they recognised discrete regions on the protein, their epitopes were mapped using a phage displayed peptide library in combination with computer-based algorithms. The presumptive epitope of one was mapped to residues 350 to 370 on HSP65 of M. bovis. The sequences selected from the peptide library by the other corresponded to three separate regions on the target protein. These recombinant antibody recognition sites are analogous to some of those that have been mapped by others using traditional monoclonal antibodies.
Dissertation (MSc)--University of Pretoria, 2008.
Veterinary Tropical Diseases
unrestricted

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Miracle, Sarah. "The effects of bias on sampling algorithms and combinatorial objects". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53526.

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Markov chains are algorithms that can provide critical information from exponentially large sets efficiently through random sampling. These algorithms are ubiquitous across numerous scientific and engineering disciplines, including statistical physics, biology and operations research. In this thesis we solve sampling problems at the interface of theoretical computer science with applied computer science, discrete mathematics, statistical physics, chemistry and economics. A common theme throughout each of these problems is the use of bias. The first problem we study is biased permutations which arise in the context of self-organizing lists. Here we are interested in the mixing time of a Markov chain that performs nearest neighbor transpositions in the non-uniform setting. We are given "positively biased'' probabilities $\{p_{i,j} \geq 1/2 \}$ for all $i < j$ and let $p_{j,i} = 1-p_{i,j}$. In each step, the chain chooses two adjacent elements~$k,$ and~$\ell$ and exchanges their positions with probability $p_{ \ell, k}$. We define two general classes of bias and give the first proofs that the chain is rapidly mixing for both. We also demonstrate that the chain is not always rapidly mixing by constructing an example requiring exponential time to converge to equilibrium. Next we study rectangular dissections of an $n \times n$ lattice region into rectangles of area $n$, where $n=2^k$ for an even integer $k.$ We consider a weighted version of a natural edge flipping Markov chain where, given a parameter $\lambda > 0,$ we would like to generate each rectangular dissection (or dyadic tiling)~$\sigma$ with probability proportional to $\lambda^{|\sigma|},$ where $|\sigma|$ is the total edge length. First we look at the restricted case of dyadic tilings, where each rectangle is required to have the form $R = [s2^{u},(s+1)2^{u}]\times [t2^{v},(t+1)2^{v}],$ where $s, t, u$ and~$v$ are nonnegative integers. Here we show there is a phase transition: when $\lambda < 1,$ the edge-flipping chain mixes in time $O(n^2 \log n)$, and when $\lambda > 1,$ the mixing time is $\exp(\Omega({n^2}))$. The behavior for general rectangular dissections is more subtle, and we show the chain requires exponential time when $\lambda >1$ and when $\lambda <1.$ The last two problems we study arise directly from applications in chemistry and economics. Colloids are binary mixtures of molecules with one type of molecule suspended in another. It is believed that at low density typical configurations will be well-mixed throughout, while at high density they will separate into clusters. We characterize the high and low density phases for a general family of discrete interfering colloid models by showing that they exhibit a "clustering property" at high density and not at low density. The clustering property states that there will be a region that has very high area to perimeter ratio and very high density of one type of molecule. A special case is mixtures of squares and diamonds on $\Z^2$ which correspond to the Ising model at fixed magnetization. Subsequently, we expanded techniques developed in the context of colloids to give a new rigorous underpinning to the Schelling model, which was proposed in 1971 by economist Thomas Schelling to understand the causes of racial segregation. Schelling considered residents of two types, where everyone prefers that the majority of his or her neighbors are of the same type. He showed through simulations that even mild preferences of this type can lead to segregation if residents move whenever they are not happy with their local environments. We generalize the Schelling model to include a broad class of bias functions determining individuals happiness or desire to move. We show that for any influence function in this class, the dynamics will be rapidly mixing and cities will be integrated if the racial bias is sufficiently low. However when the bias is sufficiently high, we show the dynamics take exponential time to mix and a large cluster of one type will form.

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Collette, Christian. "Etude expérimentales de la gélification de chaines de polystyrène : application de gels hydrophiles aux boues de forage". Paris 6, 1986. http://www.theses.fr/1986PA066047.

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Causes de la fragilité des polymères linéaires et intérêt de l'utilisation de gels obtenus par réticulation de Ps linéaire et rendus hydrophiles par sulfonation; étude expérimentales de la transition sol-gel dans un système modèle.

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Krasia, Theodora. "Synthese und kolloidale Eigenschaften neuartiger Blockcopolymere mit [beta]-Dicarbonyl-Einheiten [Beta-Dicarbonyl-Einheiten] Synthesis and colloidal properties of a novel type of block copolymers bearing [beta]-dicarbonyl [beta-dicarbonyl] residues /". Phd thesis, [S.l. : s.n.], 2003. http://pub.ub.uni-potsdam.de/2003/0021/krasia.pdf.

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Díez, Orrite Silvia. "Physico-chemical properties of polymers at interfaces". Doctoral thesis, Universitat Rovira i Virgili, 2002. http://hdl.handle.net/10803/8511.

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A polymer is a large molecule constructed from many smaller structural units called
monomers joined together by covalent bonds. Polymers have existed in natural form
since life began and those such as DNA, RNA, proteins and polysaccharides are some
of the most important macromolecules found in plant and animal life. From the earliest
times, the man has used many of these polymers as materials for providing clothing,
decoration, tools, weapons and other requirements. However, the origins of today's
polymer industry commonly are accepted as being in the nineteenth century when
important discoveries were made concerning to the modification of certain natural
polymers, as cellulose. The use of synthetic and natural polymers as stabilisers for
colloid systems (sols, dispersions, microemulsions, etc.) is becoming more important
everyday in contemporary life. Polymer additives can be applied in preconcentrations
and dehydration of suspensions in mineral processing, purification of wastewater and
even in nutritional and pharmaceutical emulsions being their importance related to the
characteristics of the process and the properties that they show. The present work aims
to develop appropriate numerical and analytical modelling techniques, which can
describe (considering the formation of loops and tails) the structure of a polymeric layer
adsorbed on heterogeneous surfaces; this adsorbed layer is an relevant factor in the
properties showed by this kind of materials. Taking into account this, the methodology
known as Single Chain Mean Field (SCMF) (originally used to study micellar
aggregates and grafted polymers) was modified to apply on polymer adsorption
problems. In this way, it was possible to calculate numerically properties that can be
experimentally measured, such as total monomer volume fraction profiles, loop and tail
volume fraction profiles, adsorbance or the thickness of the adsorbed layer. The
structure of the polymeric layer was examined both for flat and spherical (colloidal
particles) surface geometries. When compared with other well established
methodologies for the numerical simulation of polymeric systems, this new version of
SCMF was found to be more efficient due to the improved sampling of the polymer
chain configuration space.
Thus, SCMF method results, in the case of the adsorption on flat surfaces, compare well
with those obtained either with Monte Carlo simulations or with the method developed
in the 80s by Scheutjens and Fleer (SCF). Due to the lack of studies focusing to polymer
adsorption on colloidal particles, our results have been the first to present quantitative
predictions of the structure of the polymeric layer adsorbed on a spherical surface. Thus,
we have demonstrated the dependence of the adsorbed polymer layer with the size of
the colloidal particle as well as the characteristic lengths that influence on it. Finally, in
this work an analytical approach for the description of polymer-colloidal mixtures has
been developed which compares well with the numerical results obtained from the
SCMF methodology. Furthermore, the analytical approach is able to predict system
behaviours, as for example the formation of gels.
Un polímero es una molécula de grandes dimensiones formada de pequeñas unidades
llamadas monómeros, los cuales se encuentran unidos por medio de enlaces covalentes.
Los polímeros han existido de forma natural desde el comienzo de la vida, y aquellos
como el DNA, RNA o las proteínas son algunos de los polímeros más importantes
encontrados tanto en la vida animal como en la vegetal. Desde siempre el hombre ha
utilizado muchos de estos polímeros como materiales para hacer ropa, decoración,
herramientas, etc. Sin embargo, el origen de la industria de polímeros que conocemos
hoy en día se produjo en el siglo 19, gracias a importantes descubrimientos dentro de la
modificación de ciertos polímeros naturales, como la celulosa. El uso de polímeros
sintéticos y naturales como estabilizadores de sistemas coloidales (dispersiones,
microemulsiones, etc.) juega en nuestros días un papel importante. Los polímeros
utilizados como aditivos, pueden ser aplicados en preconcentraciones y deshidratación
de suspensiones dentro de procesos minerales, tratamiento de aguas residuales e incluso
los podemos encontrar dentro de la industria farmacéutica y alimentaria, donde su
importancia es debida a la procesabilidad y propiedades que ellos exhiben. El trabajo
que se presenta es orientado al desarrollo de técnicas de modelización, tanto analíticas
como computacionales, y su aplicación en la descripción (por medio de la formación de
bucles y colas) de la estructura de la capa de polímeros adsorbida en superficies
heterogéneas, siendo dicha capa de polímeros un factor importante en las propiedades
que este tipo de materiales presentan. Con este propósito, la metodología conocida
como Single Chain Mean Field, utilizada anteriormente tanto para el estudio de
agregados micelares como de polímeros anclados en superficies, ha sido modificada
para describir la adsorción de polímeros en superficies. Así se han podido calcular
numéricamente propiedades medibles experimentalmente como los perfiles de la
fracción en volumen de monómeros totales, además de los pertenecientes a los bucles y
colas, adsorbancia o el espesor de la capa adsorbida, para geometrías de la superficie
absorbente tanto plana como esférica (partículas coloidales). En su comparación con
otras metodologías, ya establecidas para la simulación numérica dentro de la física de
polímeros, la aplicación de esta nueva versión del Single Chain Mean Field (SCMF)
ha resultado ser más eficiente debido a un mejor muestreo del espacio de
configuraciones de las cadenas poliméricas. De este modo, comparando los resultados
obtenidos a partir del SCMF, con aquellos obtenidos mediante técnicas de simulación
Monte Carlo o la teoría desarrollada en los años 80 por Scheutjens y Fleer (SCF), se ha
podido encontrar un buen acuerdo en las propiedades calculadas para el caso de la
adsorción en superficies planas. Debido a la dificultad intrínseca del estudio de la
adsorción en superficies curvadas, nuestros resultados son los primeros que presentan
predicciones cuantitativas sobre la estructura de la capa que se forma sobre una
partícula coloidal. Así hemos podido comprobar la dependencia de la estructura de la
capa de polímeros adsorbidos con el tamaño de la partícula sobre la que se encuentran
adsorbidos además de las longitudes características de las cuales depende. Finalmente,
en este trabajo se ha desarrollado, también, una teoría analítica para la descripción de la
mezcla polímero-coloide. De este modo, los resultados numéricos obtenidos con el
SCMF han podido ser comparados con dicha teoría, obteniendo, de nuevo, un buen
acuerdo y predecir, además, comportamientos colectivos como la formación de geles.

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Rey, Candice. "Conditions hydrodynamiques et organisation structurale dans le dépôt formé lors de l'ultrafiltration tangentielle : application à la bioraffinerie". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI124/document.

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Les procédés de séparation membranaire, utilisés couramment dans de nombreux domaines industriels, comme l’agro-alimentaire, le traitement des eaux ou les biotechnologies, sont de plus en plus mis en œuvre dans le domaine des bioraffineries. L’ultrafiltration tangentielle, par exemple, montre un fort potentiel dans l’étape de séparation des matières premières comme les nanocristaux de cellulose pour les transformer en biomasse. Cependant, l’augmentation de la concentration en particules à la surface de la membrane limite ce procédé, entrainant la formation des phénomènes de polarisation de concentration et de colmatage, réduisant les performances de filtration. Ces travaux de thèse ont pour objectif d’améliorer la compréhension des mécanismes de formation de ces phénomènes. Deux méthodes de caractérisation couvrant les échelles nanométriques à micrométiques ont été mises au point, grâce au développement de cellules de filtration couplant l’ultrafiltration à la diffusion de rayons X aux petits angles d’une part, et à la micro vélocimétrie par images de particules d’autre part. Ces mesures effectuées in-situ lors de la filtration tangentielle de suspensions de nanocristaux de cellulose et d’argile de Laponite, ont permis de caractériser l’organisation structurale et le champ hydrodynamique au sein des couches de polarisation. La corrélation de ces résultats avec les lois de comportement rhéologique des suspensions ont permis d’accéder pour la première fois aux champs de contraintes dans les couches de polarisation de concentration et de colmatage lors du procédé
Membrane separation processes commonly used in several industrial applications, like bio and agro industries, waste water and clean water treatments, are more and more exploited in biorefinery. As an example, cross-flow ultrafiltration process shows a high potential in separation protocol of raw feed components like cellulose nanocrystals to produce biomass. This process is limited by the increase of particles concentration at the membrane surface, which conducts to phenomena named concentration polarization and fouling, which decrease the filtration performance. The PhD work objective is to bring a better understanding of the mechanisms involved in the formation of these phenomena. Two characterization methods covering length scales from nanometer to micrometer have been developed thanks to new designed tangential ultrafiltration cells allowing to link the ultrafiltration process to small angle X rays scattering and to micro particle image velocimetry. These measurement performed in-situ during ultrafiltration of nanocrystal celluloses and Laponite clay suspensions have allowed characterizing the structural organization and the velocity field within the concentration polarization layers. The correlation of these results with the rheological behavior properties of the suspensions, have permitted to access for the first time to the stress field within the concentration polarization and fouling layer during the tangential ultrafiltration process

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Bouchaudy, Anne. "Séchage microfluidique de fluides complexes : champs de concentration, diffusion collective et mesure in situ de contraintes". Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0192/document.

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Etudier le séchage est un moyen original de caractériser les propriétés de fluides complexes. Cette technique permet de concentrer continûment des fluides : d'un état dilué à un état sec. A l'échelle microfluidique, la manipulation, les observations et les processus qui entrent en jeu sont simplifiés. Ce travail de thèse s'attache à décrire le séchage de ces fluides et plus particulièrement le cas de dispersions colloïdales. Ces travaux présentent deux méthodes pour étudier l'extraction du solvant d'un fluide à l'échelle microfluidique : la micropervaporation et la goutte confinée. Ces techniques ont notamment permis de réaliser des estimations précises de coefficients de diffusion collective sur toute la gamme de concentrations pour un mélange eau/glycérol et pour une dispersion colloïdale de nanoparticules de silice chargées. Par ailleurs, le séchage induit des contraintes mécaniques conséquentes. Ces contraintes peuvent générer des déformations importantes, des phénomènes de délamination ou de fracturation du matériau solidifié. Une méthode originale de mesure in situ de contraintes a été mise en place pendant ces travaux. Les mesures réalisées avec une dispersion colloïdale modèle permettent de mettre en évidence expérimentalement l'apparition de contraintes mécaniques au moment de la transition sol/gel de la dispersion. L'augmentation de la contrainte est ensuite associée au séchage d'un gel poroélastique
Drying complex fluids is an original technique to study their properties. Solvent extraction enables the continuous concentration of fluids from a dilute to a solid state. The use of the microfluidic scale allows one to limit side effects and simplify experiments, observations and modeling. This project mainly describes the drying of colloidal dispersions in two confined geometries: microfluidic channels and confined droplets between two plates. With these two techniques, we estimate collective diffusion for a water/glycerol mixture and a model dispersion of charged silica nanoparticles over the whole concentration range. Moreover, the drying of complex fluids often induces mechanical stresses which are the root for deformation, delamination phenomena and cracks. We developed an original technique to measure these stresses in situ. For a model colloidal dispersion, we evidenced experimentally that these forces arise from a liquid to solid state transition. The increase of these stresses is then associated with the drying of a poroelastic gel

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Książki na temat "Colloidal Chains"

R, Brown H., red. Molecular simulation, fracture, gel theory. Berlin: Springer, 2002.

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(Contributor), H. R. Brown, C. Creton (Contributor), C. Y. Hui (Contributor), W. H. Jo (Contributor), E. J. Kramer (Contributor), K. Suematsu (Contributor) i J. S. Yang (Contributor), red. Molecular Simulation/Fracture/Gel Theory (Advances in Polymer Science). Springer, 2001.

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Części książek na temat "Colloidal Chains"

Biswal, Sibani Lisa, i Alice P. Gast. "Magnetically Actuated Colloidal Chains in Microchannels". W Micro Total Analysis Systems 2002, 760–62. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0504-3_53.

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Terrón-Mejía, Ketzasmin A., Roberto López-Rendón i Armando Gama Goicochea. "A New Effective Potential for Colloidal Dispersions with Polymer Chains Emerging from Mesoscopic Scale Interactions". W Communications in Computer and Information Science, 447–60. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-32243-8_31.

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Van De Mark, Michael R., Ashish Zore, Peng Geng i Fei Zheng. "Colloidal Unimolecular Polymer Particles: CUP". W Single-Chain Polymer Nanoparticles, 259–312. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2017. http://dx.doi.org/10.1002/9783527806386.ch7.

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Takahashi, M., S. Hamaguchi, H. Ito, T. Imae i T. Nakamura. "Association of block copolymers with dendritic and perfluorinated side chains in solution and at an interface". W Surface and Colloid Science, 68–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/b97084.

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Hato, Masakatsu, Hiroyuki Minamikawa, Rajesh A. Salkar i Sanae Matsutani. "Phase behavior of phytanyl-chained akylglycoside/water systems". W Trends in Colloid and Interface Science XVI, 56–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/b11629.

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Manabe, M., H. Kawamura, Y. Yamashita i S. Tokunaga. "Application of the Differential Conductivity Method: The Effect of Chain-Length of Homologous Surfactants on the Partition Coefficient of Alkanols Between Bulk Water and Micelles". W The Structure, Dynamics and Equilibrium Properties of Colloidal Systems, 63–69. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-011-3746-1_4.

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Santos, D. J. V. A. dos, i José A. N. F. Gomes. "Chain length effect on the structure of alkyltrimethylammonium chloride monolayers between two immiscible liquids". W Trends in Colloid and Interface Science XVII, 68–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/b93977.

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Carignano, G., A. Chittofrati, R. Pieri i M. Visca. "Wetting of a poly(tetrafluoroethylene) surface by aqueous solutions of perfluoropolyether carboxylic salts of different chain length". W Trends in Colloid and Interface Science XVII, 64–67. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/b93983.

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Uddin, M. H., i H. Kunieda. "Effect of poly(don the phase behavior of A–B-type silicone copolymer in water imethylsiloxane) chain length". W Trends in Colloid and Interface Science XVII, 1–5. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/b93974.

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Streszczenia konferencji na temat "Colloidal Chains"

Corredig, Milena. "Processing plant proteins colloidal structures". W 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/cyqr3105.

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Food systems need to be designed to better fit within planetary boundaries. It is not only important to find more sustainable protein sources, but also to create fully circular, robust supply chains. But this is only the beginning: new formulations will need to fit common dietary expectations. The utilization of plant-based protein ingredients present significant challenges in relation to their nutritional and technological functionalities. Today these proteins do not measure up when used as ingredients in conventional processes. Plant protein streams contain polydisperse colloids, and detailed studies of their behaviour during processing is only at their infancy. To predict their structure-function, their physical and chemical changes need to be followed at various length scales. Furthermore, for each food matrix, depending on the final product needs, it will be required to find the appropriate level of refinement and processing history, to reach the right balance between sustainability and processing/nutritional functionality. This is currently a significant knowledge gap. This talk will outline how processing dynamics at the molecular and supramolecular level, affect the interactions occurring with the various components in mixed matrices, and will aim to inspire researchers to find new processing and formulation approaches that will better fit plant-based ingredients utilization, and with this accelerate progress towards a shift to more sustainable diets.

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Yang, Tao, Ning Wu i David W. M. Marr. "Combined magneto- and opto-fluidic assembly of colloidal chains of controllable length (Presentation Recording)". W SPIE Nanoscience + Engineering, redaktorzy Kishan Dholakia i Gabriel C. Spalding. SPIE, 2015. http://dx.doi.org/10.1117/12.2187146.

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Suciu, Claudiu V., Takuzo Iwatsubo, Kazuhiko Yaguchi i Masayoshi Ikenaga. "Investigation of the Water Flow Into a Mesoporous Matrix From Hydrophobized Silica Gel". W ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-3109.

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In this work a generalized hydrodynamic theory for the water flow into a mesoporous matrix from hydrophobized silica gel is suggested. Although we examine a fluid dynamics problem, i.e., the motion of the water-gas-solid contact line, motivation for such research derives from the investigation of a novel principle of mechanical energy dissipation, called colloidal damper. Similar to hydraulic damper, this absorber has a cylinder-piston structure, but oil is replaced by a colloid consisted of a mesoporous matrix and a lyophobic liquid. Here, the mesoporous matrix is from silica gel modified by linear chains of alkyldimethylchlorosilanes and water is the associated lyophobic liquid. Mainly, the colloidal damper energy loss can be explained by the dynamic contact angle hysteresis in advancing (liquid displaces gas) and receding (gas displaces liquid); such hysteresis occurs due to the geometrical and chemical heterogeneities of the solid surface. Measuring technique of the hysteresis loop is described. From experimental data one calculates the dissipated energy, damper efficiency and the damping coefficient versus the length of the grafted molecule on the silica gel surface. Experimental results are justified by the flow analysis. Generalized hydrodynamic theory means here that the basic structure of Navier-Stokes equations is kept, but in order to include the relation between macroscopic flow and molecular interactions, slip is allowed on the solid wall. Nano-pillar architecture of the silica gel hydrophobic coating is described. During adsorption, water penetrates the pore space by maintaining contact with the top of the coating molecules (region of -CH3 groups); after that, water is forced into and partially or totally fills the space between molecules (region of -CH2 groups); in such circumstances, at the release of the external pressure, desorption occurs. Mechanism of energy dissipation is discussed. Results obtained are useful for the appropriate design of the hydrophobic coating of a mesoporous matrix which is destined to colloidal damper use.

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Fernandes, Dolfred Vijay, Sangmo Kang i Yong Kweon Suh. "Numerical Study on Electrokinetic Interaction Between a Pair of Cylindrical Colloidal Particles". W ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10582.

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Electrophoresis is the motion of dispersed particles relative to a fluid under the influence of an electric field. Presently this phenomenon of electrokinetics is widely used in biotechnology for the separation of proteins, sequencing of polypeptide chains etc. The separation efficiency of these biomolecules is affected by their aggregation. Thus it is important to study the interaction forces between the molecules. In this study we calculate the electrophoretic motion of a pair of colloidal particles under axial electric field. The hydrodynamic and electric double layer (EDL) interaction forces are calculated numerically. The EDL interaction force is calculated from electric field distribution around the particle using Maxwell stress tensor and the hydrodynamic force is calculated from the flow field obtained from the solution of Stokes equations. The continuous forcing approach of immersed boundary method is used to obtain flow field around the moving particles. The EDL distribution around the particles is obtained by solving Poisson-Nernst-Planck (PNP) equations on a hybrid grid system. The EDL interaction force calculated from numerical solution is compared with the one obtained from surface element integration (SEI) method.

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Fernandes, Dolfred Vijay, Sangmo Kang i Yong Kweon Suh. "Numerical Analysis of Electrokinetic Interaction Between a Colloidal Particle and a Planar Wall". W ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18426.

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At present electrokinetics is widely used in biotechnology for the manipulation of biomolecules, such as separation of proteins, sequencing of polypeptide chains etc. Thus it is important to study the interaction forces between the molecules and the surfaces they come in contact. In the present study we numerically solve Poisson-Nernst-Planck (PNP) model to obtain electric double layer (EDL) and its interaction when a cylindrical particle is in proximity of a planar charged wall. The axial flow field induced by the external electric field applied parallel to the planar wall is obtained from the solution of Stokes equations. The electrophoretic motion of the particle is then obtained by balancing the forces acting on the particle such as hydrodynamic, electrostatic etc. The EDL interaction force calculated using Maxwell tensor in conjunction with PNP model is validated by comparing with the one obtained from surface-element-integration method.

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Terada, Yayoi, Michio Tokuyama, Michio Tokuyama, Irwin Oppenheim i Hideya Nishiyama. "Similarities in the Dynamics of Suspensions of Monodisperse Colloidal Chains with Different Lengths Confined in the Thin Films". W COMPLEX SYSTEMS: 5th International Workshop on Complex Systems. AIP, 2008. http://dx.doi.org/10.1063/1.2897822.

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Moeendarbary, Emadaldin, K. Y. Lam i T. Y. Ng. "A New “Bounce-Normal” Boundary in DPD Calculations for the Reduction of Density Fluctuations". W ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. ASMEDC, 2008. http://dx.doi.org/10.1115/mnht2008-52069.

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Dissipative Particle Dynamics (DPD) is a mesoscopic fluid modeling method, which facilitates the simulation of the statics and dynamics of complex fluid systems at physically interesting length and time scales. Currently, there are various applications of DPD, such as colloidal suspensions, multi-phase flow, rheology of polymer chains, DNA macromolecular suspension, etc., which employ this technique for their numerical simulation. The DPD technique is capable of modeling macroscopic properties of the bulk flow very well, but difficulties arise if the flows are confined through wall-bounded regions, or when different boundaries simultaneously exist in the simulation domain. These boundaries cause negative effects on the macroscopic temperature, density and velocity profiles, as well as the shear stress and pressure distributions. In particular, the interaction of DPD particles with solid boundaries causes large density fluctuations at the near wall regions. This density distortion leads to pronounced fluctuations in the pressure and shear stress, which are not actually present. To overcome these serious deficiencies, we introduce a new method in this work, which uses a combination of randomly distributed wall particles and a novel reflection adaptation at the wall. This new methodology is simple to implement and incurs no additional computational cost. More importantly, it does not cause any distortion in the macroscopic properties. This novel reflection adaptation is a novel version of the bounce back reflection, which we shall term the bounce-normal reflection. The most important characteristic of this method is that it reduces density fluctuations near the boundaries without affecting the velocity and temperature profiles. This new method is easily applicable to any wall-bounded problem with stationary boundaries and it has a very good consistency with macroscopic features. The eventual objective of this numerical development work is to investigate suspension flow through micro/nano channels of fluidic NEMS/MEMS devices, with applications to DNA and protein separation. These micro/nano channel devices, consisting of many entropic traps, are designed and fabricated for the separation of proteins and long DNA molecules.

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Boyles, J. K., JE B. Fox i M. C. Berndt. "THE DISTRIBUTION OF GP lb AND THE STABILITY OF THE PLASMA MEMBRANE ARE DEPENDENT UPON AN INTACT MEMBRANE SKELETON". W XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643626.

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Platelets are know to have a cytoskeleton of actin filaments. We have presented evidence that they also have a membrane skeleton linked to the cytoskeletal filaments and that the membrane skeleton is linked to GP Ib-IX on the plasma membrane via actin-binding protein. In the current study, electron microscopy of thick (0.2 ym) epoxy sections was used to identify the distribution of GP lb. After various treatments, platelets were fixed and incubated with affinity-purified GP lb antibody and colloidal gold-labeled Protein-A. The entire cell surface was covered with a network of short intersecting chains of relatively evenly spaced gold particles. This was true of platelets in blood dripped directly from a vein into fixative, of washed discoid platelets, and of platelets activated by thrombin, ionophore, or cold under conditions in which aggregation did not occur. This pattern was not affected by the size of the gold label, the immunocytochemical protocol, or the fixative. The number of gold particles per cell was between 10,000 and 20,000, indicating a 1:1 ratio of label to GP lb. The distribution of GP lb was not affected by a level of cyto-chalasin B sufficient to disrupt the actin filaments of the platelet cytoskeleton. Proteolysis of actin-binding protein is known to be induced by treatment of platelets with dibucaine and by platelet activation (with either ionophore or thrombin) under conditions in which cell aggregation occurs. These same treatments caused GP lb to cluster. They also produced platelets with unstable membranes that vesiculated when the cells were subjected to shear force during centrifugation or osmotic-ally stressed during fixation. These studies show that both the distribution of GP lb and membrane stability are dependent upon the integrity of actin-binding protein and the membrane skeleton. In the high-shear environment of the blood vessel, the membrane skeleton and its linkage to GP Ib-IX and the cytoskeleton may be essential for proper platelet function.

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Webley, Ann-Dorie, Stephanie Dungan i Susan Ebeler. "Local distribution of limonene in phospholipid vesicles". W 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/qxcj6124.

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The efficacy and quality of food products is affected by the distribution of hydrophobic solutes such as flavours and bioactive compounds. In order to improve food design, it is important to determine the local distribution of these solutes and the factors that affect their stability, incorporation and release. Colloidal assemblies of phospholipids are of particular interest, as they comprise safe, widespread natural amphiphiles that can solubilize hydrophobic compounds. However, there is a lack of accurate and non-destructive methods to study the local distribution of solutes between the sample matrix elements, the aqueous phase, and the vapor phase, making it difficult to assess the effect of structure on stability and release. Short time headspace microextraction allows us to determine the local distribution of hydrophobic solutes and the effect of colloidal structure while keeping the system intact. Using thermodynamic relationships, the detected concentrations of compounds in the vapour phase are used to determine local properties within the sample matrix. The colloids of focus in this study were phosphatidylcholine vesicles which were used to extend our previous work on micellar solutions by developing a quantification method for the solubilization and retention of volatile nonpolar compounds in vesicles. The local partitioning of the aroma molecule, limonene, was investigated in vesicles of various structures, lipid compositions, and at different temperatures. Vesicles were found to be much more effective at solubilizing limonene than short-chain phosphatidylcholine micelles. They yielded vesicle-water partition coefficients of ~104Mâ€“1 while the micelles had micelle-water partition coefficients of ~103M-1. Lipid composition and vesicle size did not have a significant effect on the partitioning properties, however, reducing the limonene concentration in the vesicles lowered the partition coefficient, suggesting some interaction effect at higher limonene concentrations. In addition, with saturated lipids, limonene fluidizes the gel membrane and lowers the phase transition temperature.

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Motozawa, Masaaki, i Tatsuo Sawada. "Characteristics of Ultrasound Propagation in a Magnetic Fluid Under Uniform Magnetic Field". W ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45041.

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When an external magnetic field is applied to a magnetic fluid, some of the colloidal particles coagulate and form chain-like clusters. Properties of ultrasonic propagation wave are changed by these chain-like clusters. We carried out measurement of the ultrasonic propagation velocity in a magnetic fluid. Measurement were made by changing the magnetic field intensity from 0 mT to 570 mT, and the angle between the magnetic field direction and direction of the ultrasound propagation from 0° to 180°. The ultrasound frequencies were 1 MHz, 2 MHz and 4 MHz. Some of experimental results for the characteristics of ultrasound propagation in a magnetic fluid under a uniform magnetic field were reported.

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