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The dependence between the size of gold nanoparticle (AuNP) and the citrate to gold molar ratio (X) is still a matter of debate 65years after the seminal work by Turkevich et al. for high X values. We assume that this dispersion of results is due to the variation of certain parameters that are often not mentioned in the protocols, and to the use of a single characterization technique (dynamic light scattering (DLS) or transmission electron microscopy (TEM)). To adress definitely the question of this dependence, we have synthesized AuNPs with very precise protocols ensuring that the only parameters to be modified are X and the sequence of reagent addition. We have then studied, for the first time, the dependence of the size with X quantitatively with a multimodal approach (UV-Visible spectroscopy, DLS and TEM) for 2 synthetic routes differing only by the sequence of reagent addition. We show unambiguously that AuNPs' size decay monotonically, with X whatever the order of reagent addition. It allows us to exclude the occurrence of a measurable discontinuity for a peculiar value of X that prompted some authors to postulate the existence of two different reaction pathways when the citrate to gold molar ratio is around this value. In contrast, our result is in line with one reaction pathway, likely a "seed-mediated" growth mechanism, which should leads to monotonic size decrease. Also, we note that our result agrees with the sole available theoretical prediction (Kumar et al., 2007) on the whole range of X. Despite this apparent agreement, we point some contradictions between recent experimental results and basal hypothesis of this model.

International audience; Neutron reflectivity has been used to investigate the effect of shear on the conformation of hydrogenated polystyrene chains end-grafted on a silicon wafer and covered by a deuterated polystyrene melt, in the grafting regime where the grafted chains at equilibrium extend in the bulk up to their radius of gyration. An experimental setup has been built to shear the samples above their glass transition temperature and then quench them rapidly after the shear. The flow-induced distorted conformation of the end-tethered chains was characterized by neutron reflectivity. We show that the effect of the shear is a decoupling between the grafted chains and the bulk chains which leads to a strong slip of the polymer melt at the solid interface.

International audience; Malignancies represent a major cause of morbidity and mortality in human immunodeficiency virus (HIV)-infected patients. The introduction of combined antiretroviral therapy has modified the spectrum of malignancies in HIV infection with a decreased incidence of acquired immunodeficiency syndrome (AIDS) malignancies such as Kaposi's sarcoma and non-Hodgkin's lymphoma due to partial immune recovery and an increase in non-AIDS-defining malignancies due to prolonged survival. Management of HIV-infected patients with cancer requires a multidisciplinary approach, involving both oncologists and HIV physicians to optimally manage both diseases and drug interactions between anticancer and anti-HIV drugs. The French CANCERVIH group presents here a review and an experience of managing non-AIDS malignancies in HIV-infected individuals.

BACKGROUND: Kaposi sarcoma (KS) remains a frequent cancer in human immunodeficiency virus (HIV)-positive patients starting combination antiretroviral therapy (cART). We examined incidence rates and risk factors for developing KS in different periods after starting cART in patients from European observational HIV cohorts. METHODS: We included HIV-positive adults starting cART after 1 January 1996. We analyzed incidence rates and risk factors for developing KS up to 90 and 180 days and 1, 2, 5, and 8 years after cART start and fitted univariable and multivariable Cox regression models. RESULTS: We included 109 461 patients from 21 prospective clinical cohorts in Europe with 916 incident KS cases. The incidence rate per 100 000 person-years was highest 6 months after starting cART, at 953 (95% confidence interval, 866-1048), declining to 82 (68-100) after 5-8 years. In multivariable analyses adjusted for exposure group, origin, age, type of first-line regimen, and calendar year, low current CD4 cell counts increased the risk of developing KS throughout all observation periods after cART initiation. Lack of viral control was not associated with the hazard of developing KS in the first year after cART initiation, but was over time since starting cART increasingly positively associated (P < .001 for interaction). CONCLUSION: In patients initiating cART, both incidence and risk factors for KS change with time since starting cART. Whereas soon after starting cART low CD4 cell count is the dominant risk factor, detectable HIV-1 RNA viral load becomes an increasingly important risk factor in patients who started cART several years earlier, independently of immunodeficiency.

International audience; We aim at combining high coercivity magnetic nanowires in a polymer matrix in a view to fabricate rare-­‐earth free bonded magnets. In particular, our aim is to fabricate anisotropic materials by aligning the wires in the polymer matrix. We have explored the different parameters of the fabrication process in order to produce a material with the best possible magnetic properties. We show that the choice of a proper solvent allows obtaining stable nanowire suspensions. The length and the type of the polymer chains play also an important role. Smaller chains (M w

International audience; Scattering functions of sodium sulfonated polystyrene (NaPSS) star-branched polyelectrolytes with high sulfonation degrees were measured from their salt-free aqueous solutions, using the Small Angle Neutron Scattering (SANS) technique. Whatever the concentration c, they display two maxima. The first, of abscissa q 1 *, is related to a position order between star cores and scales as q 1 * 9 c 1/3. The second, of abscissa q 2 *, is also observed in the scattering function of a semi-dilute solution of NaPSS linear polyelectrolytes. In the dilute regime (c < c*, non-overlapping stars), peak abscissa does not depend on concentration c and is just an intramolecular characteristic associated with the electrostatic repulsion between arms of the same star. In the semi-dilute regime, due to the star interpenetration, the scattering function – through the peak position, reflects repulsion between arms of the same star or of different stars. The c threshold between these distinct c-dependencies of q 2 * in the dilute and semi-dilute regimes is estimated as c*. Just as simple is the measurement of the geometrical radius R of the star obtained from the q 1 * value at c* through the relation 2R = 2π/q 1 *. By considering NaPSS stars of the same functionality with different degrees of polymerization per arm N a , we find R scaling linearly with N a , suggesting an elongated average conformation of the arms. This is in agreement with theoretical predictions and simulations. Meanwhile the value of q 2 * measured in the dilute regime does not allow any inhomogeneous counterion distribution inside the stars to be revealed.

The question of the influence of nanoparticles (NPs) on chain dimensions in polymer nanocomposites (PNCs) has been treated mainly through the fundamental way using theoretical or simulation tools and experiments on well-defined model PNCs. Here we present the first experimental study on the influence of NPs on the polymer chain conformation for PNCs designed to be as close as possible to industrial systems employed in the tire industry. PNCs are silica nanoparticles dispersed in a styrene-butadiene-rubber (SBR) matrix whose NP dispersion can be managed by NP loading with interfacial coatings or coupling additives usually employed in the manufacturing mixing process. We associated specific chain (d) labeling, and the so-called zero average contrast (ZAC) method, with SANS, in situ SANS and SAXS/TEM experiments to extract the polymer chain scattering signal at rest for non-cross linked and under stretching for cross-linked PNCs. NP loading, individual clusters or connected networks, as well as the influence of the type, the quantity of interfacial agent and the influence of the elongation rate have been evaluated on the chain conformation and on its related deformation. We clearly distinguish the situations where the silica is perfectly matched from those with unperfected matching by direct comparison of SANS and SAXS structure factors. Whatever the silica matching situation, the additive type and quantity and the filler content, there is no significant change in the polymer dimension for NP loading up to 15% v/v within a range of 5%. One can see an extra scattering contribution at low Q, as often encountered, enhanced for non-perfect silica matching but also visible for perfect filler matching. This contribution can be qualitatively attributed to specific h or d chain adsorption on the NP surface inside the NP cluster that modifies the average scattering neutron contrast of the silica cluster. Under elongation, NPs act as additional cross-linking junctions preventing chain relaxation and giving a deformation of the chain with the NP closer to a theoretical phantom network prediction than a pure matrix.

We report on the influence of parameters controlling filler dispersion and mechanical reinforcement in model nanocomposites. We elaborate a series of nanocomposites and present a structural characterization of silica dispersion in polymer matrix for several particle sizes and polymer matrices, at all relevant scales, by coupling Small Angle X-ray Scattering and Transmission Electronic Microscopy. The mechanical properties are investigated in the linear regime by coupling Dynamical Mechanical Analysis and plate/plate rheology. The results show that: (i) for all filler sizes and matrices, a structural transition is observed from non-connected fractal aggregates at low silica concentration to connected network at high particle content. (ii) In the dilute regime, the reinforcement implies a polymer chain contribution with different possible origins: increase of entanglements density for PS and increase of friction coefficient for PMMA. (iii) In the concentrated regime, for a given polymer, the reinforcement amplitude can be tuned by the rigidity of the filler network, which directly depends on the particle–particle interaction.

International audience; OBJECTIVES: Employment status is a major predictor of health status and living conditions, especially among HIV-infected people, a predominantly working-aged population. We aimed to quantify the risk of work cessation following HIV diagnosis in France in 2004-2010 and to measure the respective burden of HIV-related characteristics and of associated comorbidities on this risk. DESIGN: We used data from a multicenter cohort made of a diversified sample of recently diagnosed HIV-1-infected adults, antiretroviral treatment-naive at baseline in 2004-2008 (ANRS-COPANA cohort). Detailed information on living conditions and clinical and biological characteristics were collected prospectively. METHODS: The risk of work cessation among the 376 working-aged participants employed at baseline was estimated using the Kaplan-Meier method. Characteristics associated with the risk of work cessation were identified using multivariate Cox models. RESULTS: The cumulative probability of work cessation reached 14.1% after 2 years and 34.7% after 5 years. Diabetes, hypertension and, to a lesser extent, signs of depression were associated with increased risks of work cessation after accounting for socio-occupational characteristics [adjusted hazard ratios (95% confidence interval): 5.7 (1.7-18.8), 3.1 (1.5-6.4) and 1.6 (0.9-2.9), respectively]. In contrast, HIV disease severity and treatment and experience of HIV-related discrimination were not statistically associated with the risk of work cessation. CONCLUSION: The risk of work cessation during the course of HIV disease has remained substantial in the most recent period in France. Comorbidities, but not characteristics of HIV disease itself, substantially affect chances of maintaining employment. This provides insights into strategies for limiting the burden of HIV disease for individuals and society.

We review, based on structural information, the mechanisms involved when putting in contact two nano-objects of opposite electrical charge, in the case of one negatively charged polyion, and a compact charged one. The central case is mixtures of PSS, a strong flexible polyanion (the salt of a strong acid, and with high linear charge density), and Lysozyme, a globular protein with a global positive charge. A wide accurate and consistent set of information in different situations is available on the structure at local scales (5-1000Å), due to the possibility of matching, the reproducibility of the system, its well-defined electrostatics features, and the well-defined structures obtained. We have related these structures to the observations at macroscopic scale of the phase behavior, and to the expected mechanisms of coacervation. On the one hand, PSS/Lysozyme mixtures show accurately many of what is expected in PEL/protein complexation, and phase separation, as reviewed by de Kruif: under certain conditions some well-defined complexes are formed before any phase separation, they are close to neutral; even in excess of one species, complexes are only modestly charged (surface charges in PEL excess). Neutral cores are attracting each other, to form larger objects responsible for large turbidity. They should lead the system to phase separation; this is observed in the more dilute samples, while in more concentrated ones the lack of separation in turbid samples is explained by locking effects between fractal aggregates. On the other hand, although some of the features just listed are the same required for coacervation, this phase transition is not really obtained. The phase separation has all the macroscopic aspects of a fluid (undifferentiated liquid/gas phase) - solid transition, not of a fluid-fluid (liquid-liquid) one, which would correspond to real coacervation). The origin of this can be found in the interaction potential between primary complexes formed (globules), which agrees qualitatively with a potential shape of the type repulsive long range attractive very short range. Finally we have considered two other systems with accurate structural information, to see whether other situations can be found. For Pectin, the same situation as PSS can be found, as well as other states, without solid precipitation, but possibly with incomplete coacervation, corresponding to differences in the globular structure. It is understandable that these systems show smoother interaction potential between the complexes (globules) likely to produce liquid-liquid transition. Finally, we briefly recall new results on Hyaluronan/Lysozyme, which present clear signs of coacervation in two liquid phases, and at the same time the existence of non-globular complexes, of specific geometry (thin rods) before any phase separation. These mixtures fulfill many of the requirements for complex coacervation, while other theories should also be checked like the one of Shklovskii et al.

We have studied by small angle X-ray scattering (SAXS) the structure of salt-free polyelectrolytes solutions containing monovalent and divalent counterions. We have considered mixtures of sulfonated polystyrene with monovalent (Na+) and divalent (Ca2+) counterions and measured the position of the scattering peak, q*, as a function of the monomer concentration cp and the monovalent/divalent content. The aim is to understand the variations observed in q* position when the valence of the counterions is gradually increased. This work is a continuation of a previous study in which first measurements were performed on a rather small number of sodium−PSS/calcium−PSS mixtures. In the present work, we used synchrotron radiation to improve the quality of the data and vary the monovalent/divalent ratio with a much finer step. Indeed this gives new interesting results in the ranges of low and large divalent content. We analyzed SAXS results through the isotropic model and scaling approach description introduced by de...

Interferon-α administration during structured treatment interruptions (STIs) was studied in a phase III trial. We randomized 168 chronically infected HIV undetectable under combined anti-retroviral therapy patients to have three STIs with or without α-interferon. The number of patients who had to resume treatment during post-STI follow-up was not significantly different between the two arms. Patients with a low CD4 nadir and a high baseline HIV-DNA had a higher risk of treatment resumption in the interferon arm.

The risk of Hodgkin lymphoma (HL) is increased in patients infected with HIV-1. We studied the incidence and outcomes of HL, and compared CD4+ T-cell trajectories in HL patients and controls matched for duration of combination antiretroviral therapy (cART). A total of 40 168 adult HIV-1–infected patients (median age, 36 years; 70% male; median CD4 cell count, 234 cells/μL) from 16 European cohorts were observed during 159 133 person-years; 78 patients developed HL. The incidence was 49.0 (95% confidence interval [CI], 39.3-61.2) per 100 000 person-years, and similar on cART and not on cART (P = .96). The risk of HL declined as the most recent (time-updated) CD4 count increased: the adjusted hazard ratio comparing more than 350 with less than 50 cells/μL was 0.27 (95% CI, 0.08-0.86). Sixty-one HL cases diagnosed on cART were matched to 1652 controls: during the year before diagnosis, cases lost 98 CD4 cells (95% CI, −159 to −36 cells), whereas controls gained 35 cells (95% CI, 24-46 cells; P < .0001). The incidence of HL is not reduced by cART, and patients whose CD4 cell counts decline despite suppression of HIV-1 replication on cART may harbor HL.

We studied by small-angle neutron scattering (SANS) the polymer chain conformation in model silica/polystyrene (PS) nanocomposites. Using the zero average contrast method, we can properly match silica signal to directly measure the form factor of a single PS chain. An important effort has been put to eliminate the silica scattering using two distinct approaches (called respectively “three” and “four” components methods) leading to analogue results. By combining SANS data with small-angle X-ray scattering (SAXS) measurements and transmission electronic microscopy (TEM) images on the same samples, we obtain a very clear result about the effect on polymer chain conformation of the filler dispersion, either at low filler volume fraction, where silica arrange in small aggregates or at higher concentration where it forms a connected network. From SANS the chain conformation in nanocomposites is identical to the one without silica in a large q range illustrating that the chain conformation remains independent of...

The relative roles of immunodeficiency, HIV viral load, and combination antiretroviral therapy (cART) in the onset of individual cancers have rarely been examined. We examined the effect of these factors on the risk of specific cancers in patients infected with HIV-1.We investigated the incidence of both AIDS-defining cancers (Kaposi's sarcoma, non-Hodgkin lymphoma, and cervical cancer) and non-AIDS-defining cancers (Hodgkin's lymphoma, lung cancer, liver cancer, and anal cancer) in 52 278 patients followed up in the French Hospital Database on HIV cohort during 1998-2006 (median follow-up 4.9 years, IQR 2.1-7.9; 255 353 person-years). We tested 78 models with different classifications of immunodeficiency, viral load, and cART with Poisson regression.Current CD4 cell count was the most predictive risk factor for all malignancies apart from anal cancer. Compared with patients with CD4 count greater than 500 cells per microL, rate ratios (RR) ranged from 1.9 (95% CI 1.3-2.7) for CD4 counts 350-499 cells per microL to 25.2 (17.1-37.0) for counts less than 50 cells per microL for Kaposi's sarcoma (p0.0001), from 1.3 (0.9-2.0) to 14.8 (9.7-22.6) for non-Hodgkin lymphoma (p0.0001), from 1.2 (0.7-2.2) to 5.4 (2.4-12.1) for Hodgkin's lymphoma (p0.0001), from 2.2 (1.3-3.6) to 8.5 (4.3-16.7) for lung cancer (p0.0001), and from 2.0 (0.9-4.5) to 7.6 (2.7-20.8) for liver cancer (p0.0001). For cervical cancer, we noted a strong effect of current CD4 (RR 0.7 per log(2), 95% CI 0.6-0.8; p=0.0002). The risk of Kaposi's sarcoma and non-Hodgkin lymphoma increased for current plasma HIV RNA greater than 100 000 copies per mL compared with patients with controlled viral load (RR 3.1, 95% CI 2.3-4.2, p0.0001; and 2.9, 2.1-3.9, p0.0001, respectively), whereas cART was independently associated with a decreased incidence (0.3, 0.2-0.4, p0.0001; and 0.8, 0.6-1.0, p=0.07, respectively). The RR of cervical cancer for those receiving cART was 0.5 (0.3-0.9; p=0.03). The risk of anal cancer increased with the time during which the CD4 count was less than 200 cells per microL (1.3 per year, 1.2-1.5; p=0.0001), and viral load was greater than 100 000 copies per mL (1.2 per year, 1.1-1.4, p=0.005).cART would be most beneficial if it restores or maintains CD4 count above 500 cells per microL, thereby indicating an earlier diagnosis of HIV infection and an earlier treatment initiation. Cancer-specific screening programmes need to be assessed in patients with HIV.Agence Nationale de Recherches sur le SIDA et les hépatites (ANRS), INSERM, and the French Ministry of Health.

International audience; We demonstrate in this paper the influence of solvent quality on the structure of the semi-dilute solution of a hydrophobic polyelectrolyte, partially sulfonated Poly-Styrene Sulfonate. Two solvents are used: (i) one mixture of water and an organic solvent: THF, which is also slightly polar; (ii) DMSO, a polar organic solvent. In case (i), it is shown by SAXS study that the structure - namely the scattering from all chains, characterised by a maximum (“polyelectrolyte peak”), of the aqueous hydrophobic polyelectrolyte solutions (PSS) depends on the solvent quality through the added amount of organic solvent THF. This dependence is more pronounced when the sulfonation rate is low (more hydrophobic polyelectrolyte). It is proposed that when THF is added, the chain conformation evolves from the pearl necklace shape already reported in pure water, towards the conformation in pure water for fully sulfonated PSS, which is string-like as also reported previously. On the contrary, for a hydrophilic polyelectrolyte, AMAMPS, no evolution occurs with added THF in the aqueous solution. In case (ii), it is shown directly by SANS study that PSS can behave as a classical solvophilic polyelectrolyte when dissolved in an organic polar solvent such as DMSO: the structure (total scattering) as well as the form factor (single chain scattering measured by SANS using the Zero Average Contrast method) of the PSS chains is independent of the charge content in agreement with Manning condensation, and identical to the one of a fully charged PSS chain in pure water, which has a classical polyelectrolyte behaviour in the semi-dilute regime.

International audience; A new bis-urea based supramolecular polymer is reported and shown by viscosimetry, neutron scattering (SANS) and calorimetry (ITC) to self-assemble in a wide range of solvents, encompassing the polarity scale from water to toluene. The presence of both hydrogen bonding and hydrophobic groups ensures that self-assembly occurs in water, aprotic polar solvents or non-polar solvents. Both the driving force for the assembly and the exact structure of the filaments is solvent dependent, but whatever the solvent, long rigid filaments are formed in dynamic equilibrium with the monomer

The advantage of small angle neutron scattering associated with isotopic labelling through deuteration is illustrated in the case of mixed systems, created by associating already well-known systems of characteristic structures; this is also important for applications. Our first mixed system associates charged polymer chains, polyelectrolytes (here polystyrene sulfonate, PSS), with oppositely charged particles, proteins (here lysozyme). Different fractions of deuterated water (D 2 O) mixed with normal water are used to match the scattering length density of the protein or of the polymer in non-deuterated or deuterated version. First, this allows us to separate the protein and the polymer signal: we can then distinguish a case where the structures of each species alone in water are hardly modified by mixing, except for interconnections yielding a gel , and a case inducing complete change into a structure common to both species, made of aggregated globules . Second, using, for counterions of the polyions, deuterated TetraMethylAmmonium, together with matching both protein and polymer, we establish unambiguously the counterion release into the solvent. Third, matching only a fraction of polymer chains, the other being deuterated, we extrapolate at zero deuterated fraction their form factor and describe the chain conformation inside the complexes. Fourth, we illustrate the possibilities of modelling the signal on a second example of mixed system: a nanocomposite made of silica particles surrounded by polymer dispersed into a deuterated polymer matrix. Chains are then visible in such reinforced polymer system, in particular when it is submitted to elongation: we discuss a possible model for an ideal system, introducing the scattering contribution from deformed chains, another subject studied at LLB. To cite this article: F. Boue et al., C. R. Physique 8 (2007).

We show in this paper how the combination of SANS and freeze-fracture electron microscopy (FFEM) is a powerful tool to picture the structure of very turbid sample liquids at spatial scales lying from a few A to several microns. In a given range of chain size and species concentrations, primary complexes in the shape of globules are observed by both techniques. SANS allows a precise quantitation of size, inner structure, and composition of these globules, as well as aggregated structure of the globules at larger scales, which is fractal-like, with a Hausdorff dimension 2.1 characteristic of Reaction Limited Aggregation (RCLA). The existence of aggregates is seen by FFEM, but most of all FFEM shows the lack of any further structure at larger scale, up to the micrometer size.

International audience; Nano-hybrid hydrogels were prepared by cross-linking polymerization of N,N-dimethylacrylamide (DMA) within a dispersion of silica nano-particles. Working at constant polymer/water ratio, the mechanical properties of hydrogels can be finely tuned by changing either the level of covalent cross-linker and/or the amount of particles that act as physical cross-linkers through specific adsorption of PDMA chains. Whatever is the cross-linking ratio (from 0 to 1 mol%), the introduction of silica nano-particles dramatically improves the mechanical behavior of hydrogels with a concomitant increase of stiffness and nominal strain at failure. The physical interactions being reversible in nature, the dynamics of the adsorption/desorption process of PDMA chains directly controls the time-dependence of the mechanical properties. Small angle neutron scattering experiments, performed in contrast matching conditions, show that silica particles, which repel themselves at short range, remain randomly dispersed during the formation of the PDMA network. Although PDMA chains readily interact with silica particles, no significant variation of the polymer concentration was observed in the vicinity of silica surfaces. Together with the time dependence of physical interactions pointed out by mechanical analyses, this result is attributed to the moderate adsorption energy of PDMA chains with silica surfaces at pH 9. From 2D SANS experiments, it was shown that strain rapidly gives rise to a non affine deformation of the hybrid network with shearing due to the transverse compression of the particles. After loading at intermediate deformation, the particles recover their initial distribution due to the covalent network that is not damaged in these conditions. That is no longer true at high deformation where residual anisotropy is observed.

We report the formation of well-defined and uniformly sized nano- and microparticles in aqueous solutions of oppositely charged polyelectrolytes and surfactants. Such mixed aqueous solutions are currently the focus of much attention because of the large number of applications in which they are involved. [1,2] The particles that we have obtained are spherical and possess an internal liquid-crystal-like structure. The radius of the particles is independent of the polymer concentration but increases exponentially with the surfactant concentration. The particle size can therefore be varied over a broad range, from 10 nm up to several micrometers. Here, we discuss the conditions used to synthesize these particles. Upon mixing the polyelectrolytes and surfactants, two distinct behaviors are observed. First, precipitation occurs above a critical concentration for both the polymer and the surfactant when the two species are oppositely charged (Fig. 1). In contrast to the usual precipitation of salts, or even mixtures of two surfactants, this precipitation does not occur at a point where the ionic concentrations of the two species are close. In the following discussion we denote the surfactant and polymer ion concentrations by Cs and Cp, respectively. The phase separation has an “associative” character: at large Cp, the surfactant concentration threshold Cs* is roughly independent of

We report here the structure of complexes made of proteins (lysozyme, positively charged) and polyelectrolytes (PSSNa, negatively charged). We stay in conditions where the volume fractions of the components are of the same order and where PSS concentrations correspond to a semidilute regime. The final complexes structure is determined by SANS. We obtain three main types of structures: (i) For a protein excess and for long polyelectrolyte chains, the network preformed by PSS chains still exists but chains are partially shrunk due to cross-linking by lysozyme. Macroscopically, samples are gelled. (ii) For a protein excess and for short polyelectrolyte chains, PSS chains are locally shrunk and do not form a network anymore. Lysozyme and PSS chains are embedded in dense 3-D aggregates that arrange in a fractal network at a larger scale. Macroscopically, samples are liquid. (iii) For a polyelectrolyte excess and whatever the chain length, the internal structure of the lysozyme changes. After an initial strong electrostatic binding, lysozyme is progressively unfolded thanks to a hydrophobic contact with PSS. The two chainlike objects are finally organized in a homogeneous costructure. Macroscopically, samples are liquids.

We have investigated by small-angle X-ray and neutron scattering the structure of salt-free aqueous solutions of sulfonated polystyrene with variable fractions of monovalent (sodium, Na) and divalent (calcium, Ca) counterions. We follow the variation of the position of the maximum in the scattered intensity, q*, as a function of the concentration, c, and the fraction of Ca counterions. A relevant parameter is the degree of condensation of Na and Ca counterions in the different mixtures. We survey the literature and check that, in the case of monovalent counterions, the variation of q* with c can be described by the scaling theory of Dobrynin, Colby, and Rubinstein, provided the counterion condensation is included according to the Manning-Oosawa approach. Scattering data from mixed valence systems are still in agreement with this scaling model at lower concentrations, except for pure CaPSS 2 aqueous solutions. For increasing concentration, a discrepancy is enhanced that extends toward higher Ca fractions. This indicates that counterion condensation is not the only process. Another possible one is a retraction of the macroions due to divalent counterions that induce bridging-type correlations between monomers, as already observed on the form factors of CaPSS 2 and NaPSS plus added CaCl 2 salt. Such a retraction modifies the scaling, in particular, via a change in the overlap concentration c*. Furthermore, it is noticeable that q* measurements have to be handle with care. We show that misinterpretation of the characteristic maximum in the small-angle scattering of polyelectrolyte solutions may occur, especially at high concentration, if the contribution of the condensed counterions to the total scattering function is predominant.

Polymer chains are grafted from silica nanobeads. The method consists in grafting first the initiator molecules on the silica surface. Then, the polymerization of styrene or n-butyl methacrylate using Atom Transfer Radical Polymerization, is conducted. The nanoparticles are kept in solution during the whole process to avoid irreversible aggregation. The state of dispersion of the grafted silica nanoparticles is followed by Small Angle Neutron Scattering, as well as the quantity and the spatial organisation of the polymer. This is done during the functionalisation and the polymerization, but also after purification where free polymer chains are eliminated. This permits to reach a quantitative level of SANS analysis from these purified particles, which is compared to chemical data given by Size Exclusion Chromatography and Thermogravimetric analysis.

Polymer chains were grafted from silica beads (colloidal sol in dimethylacetamide) by atom transfer radical polymerization (ATRP), via the ‘grafting from’ method. The grafting of the initiator onto the silica surface was done in two steps. First, thiol-functionalization of the surface was achieved via silanization with a mercaptopropyl triethoxysilane. Second, we performed an over-grafting of the surface by reacting the thiol with 2-bromoisobutyryl bromide to generate the halogen-functional ATRP initiator. The nanoparticles were kept in solution (in the same solvent) at each stage of the functionalization (even during the purification steps), as this is the only way to avoid irreversible aggregation. Then, the polymerization of styrene was conducted. Control of both the molecular weight and the density of grafted chains can be achieved by this method. Careful characterization such as gel permeation chromatography, 29 Si CP/MAS NMR, elemental analysis, infrared spectroscopy and thermo-gravimetric analysis is performed. The state of dispersion of the grafted nanoparticles is followed in details by small angle neutron scattering and results obtained from this technique are presented here as well as the way the SANS data can be treated. Connection is systematically done between the information provided by this technique and the improvement of the synthetic procedure.

Polymer chains are grafted from silica beads (colloidal sol in dimethylacetamide) by atom transfer radical polymerization (ATRP). The method consists of grafting first the initiator molecules on the silica surface (“grafting from” method), in two steps. First, thiol-functionalization of the surface was achieved via silanization with a mercaptopropyl triethoxysilane. Second, we performed an overgrafting of the surface by reacting the thiol with 2-bromoisobutyryl bromide to generate the halogen-functional ATRP initiator. From that, the polymerization of styrene was conducted. Control of both the molecular weight and the density of grafted chains can be achieved by this method. The other originality of this work is that we keep the nanoparticles in solution at each stage of the procedure (even during the purification steps), as this is the only way to avoid irreversible aggregation. The state of dispersion of the grafted nanoparticles is followed by small-angle neutron scattering. Characterizations such as g...

International audience; Aromatic stacking and hydrophobic interactions are the driving forces for the reversible self‐assembly of an amphiphilic perylene derivative in water to form a linear polymer (see schematic representation). The structure of the assemblies has been elucidated by small‐angle neutron scattering, and the association strength determined by NMR and fluorescence spectroscopies.

We investigate, using small-angle neutron scattering (SANS), the polymer concentration fluctuations in a particular type of end-linked polystyrene gels, in the swollen state. These gels are obtained from the cross-linking of well-defined end-capped low-polydispersity chains end-linked through a trifunctional cross-linking agent. Polystyrene precursor chains of three different molecular weights, namely 5.5K, 10K, and 15.2K, were used. The scattering at low scattering vectors is expected to come from static concentration fluctuations. Here the intensity displays a dominant scattering characterized either at low q by a unique correlation length or on a wider q range by a set of two correlation lengths, one of which has been locked to the correlation length in the semidilute solution of same polymer concentration. We note ξhet as a characterization of swelling heterogeneity, the unique low q correlation length, or the larger one in the double length fit. For both fits, the variation of ξhet with the polymer v...

In this study, we have directly determined for the first time the structure and the chain conformation of hyaluronan, a model semirigid polyelectrolyte polysaccharide. At high ionic strength, detailed information on the chain flexibility has been obtained from combined light and small-angle neutron scattering experiments by applying different fitting methods based upon expressions for a single-chain scattering function of a wormlike chain without excluded volume. Particular attention has been given to the determination of the intrinsic persistence length, L0, and a value close to 90 A was found using the different fitting procedures. Without screening (i.e., at low ionic strength), the measured total persistence length appears increased by at least the amount predicted by Odijk for the electrostatic contribution, Le (∼κ-2, square of the Debye−Huckel screening length). This would mean this model was checked using classical polyelectrolytes. At high ionic strength the scattered intensity crosses over, with ...

Les polymeres a l'etat amorphe, liquide ou vitreux forment des materiaux desordonnes aux proprietes specifiques. Les larges gammes de distance impliquees, locale, senti-locale, intermediaire, globale, de 1 a 500 nm font de la Diffusion de Neutrons aux Petits Angles (DNPA°, mais aussi de la diffusion inelastique par temps de vol et echo de spin, et de la reflectivite des outils d'etude privilegies Nous detaillons le cas de la chaine gaussienne dans le fondu, sa statique et sa dynamique a l'etat libre puis le cas de la chaine vermiforme. Nous considererons ensuite les solutions en bon solvant, en statique et dynamique, les solutions de polyelectrolytes, l'enchevetrement et la reptation, les reseaux et gels de chaines reticulees. Ce qui nous amenera a des exemples de diffusion par des objets deformes, ou sous ecoulement (rheo-DNPA). Nous decrirons brievement le cas de systemes mixtes et les avantages de la variation de contraste, ainsi que l'etude des interfaces par DNPA ou par reflectivite.

We report on small-angle neutron scattering measurements obtained in situ on three-dimensional aqueous foams stabilized by sodium dodecyl sulfate. Isotropic as well as anisotropic scattering data have been collected for two kinds of foams: wet foams in the steady-state regime of constant gas bubbling and dry foams under free draining conditions. Reliable scattering spectra were obtained within a few minutes, even for very dry foams. All spectra have a basic I(q) ∼ q-4 behavior on which a foam specific structure is superposed. The q-4 decrease at low q can be interpreted in terms of a Porod law from which the average bubble size is determined for both wet and dry foams. For wet foams, the intensity is modulated at high q by the structural organization of the surfactants in the liquid fraction of the foam (micelles). Remarkably, for dry foams only, the structure also appears at intermediate q, corresponding to the film thickness. This structure can be enhanced by using deuterated sodium dodecyl sulfate to ...

Neutron- and light-scattering measurements reveal that large-amplitude oscillatory shear flow can drive entangled polymer solutions to a completely microphase-separated state with sharp interfacial boundaries while steady shear flow does not. For steady shear flow, interfacial boundaries remain less well-defined for all shear rates measured, indicating less complete phase separation. Results are discussed within the context of recent theoretical models.

The soft matter group of LLB is centered on Small Angle Neutron Scattering (SANS). It is in charge of three classical SANS facilities (one annular detector and two XY detectors) and one polarized neutron SANS, and is developing a new USANS diffractometer. The group is also connected withneutron reflectivity, and to a lesser extent to inelastic scattering (spin echo, time of flight). In the field of soft matter, the expertise has been for many years focused on polymer solutions (neutral and charged), adsorbed polymers, polymer melts, and liquid crystalline polymers, witha focus on the effect of mechanical deformation (“rheo-SANS”). More recently, such deformation effects have been studied also on polymer latex films and latex-silica composites. We have chosento present this work here, which is at the boundary between polymer and colloid science, since interactions between silica particles in the films are involved and control partly the reinforcement of the polymer film. We will balance this examp...

ObjectiveTo compare the efficacy and safety of a triple nucleoside combination to a protease inhibitor-containing triple regimen as first-line antiretroviral therapy (ART) in HIV-1-infected patients.DesignOpen-label study in HIV-1-infected ART-naive adults, randomized to receive either Combivir® (lamivudine 150 mg/zidovudine 300 mg twice daily) + abacavir (300 mg twice daily), or Combivir® + nelfinavir (750 mg every 8 h) for 48 weeks. Plasma HIV-1 RNA, CD4 cell count and adverse events were assessed at baseline and weeks 4, 8, 16, 24, 32, 40 and 48.Results195 subjects (131 men, 64 women), median age 34 years, were randomized: 98 received combivir/abacavir and 97 combivir/nelfinavir. Baseline median plasma HIV-1 RNA was 4.2 log10copies/ml [Interquartile range (IQR): 3.7-4.5.2] and 4.1 log10copies/ml (IQR: 3.8–4.6), respectively. Baseline median CD4 cell count was 387 cells/mm3(IQR: 194–501) and 449 cells/mm3(IQR: 334–605), respectively. Nine patients (3 vs 6, respectively) did not start treatment or did not have any available efficacy data. At week 48, using the intent to treat analysis (switch/missing equals failure), plasma HIV-1 RNA was 3, respectively. Possible hypersensitivity reactions to abacavir were reported in four subjects (4%).ConclusionThe triple nucleoside combination combivir/abacavir is well tolerated as a first-line ART regimen in HIV-1-infected adults, with comparable antiviral activity to a nelfinavir-containing regimen at week 48.

Aqueous solutions of a well-defined poly(N-isopropylacrylamide-co-sodium 2-acrylamido-methylpropanesulfonate) (NIPAM/NaAMPS in a 95/5 molar ratio) have been investigated by means of small-angle neutron scattering (SANS) and rheological experiments as a function of temperature ( 25°C\(\)T\(\) 60°C) and polymer concentration ( 0.5wt% \(\)C\(\) 12wt%). The solutions remain optically transparent and isotropic over the whole temperature range, in contrast with the homopolyNIPAM which precipitates above its lower critical solution temperature (LCST = 32°C). Upon addition of salt, the systems undergo a micro-macrophase separation. At temperatures above 45°C, the SANS spectra exhibit a sharp peak at a scattering wave vector, qmax, which increases slightly with temperature. At high temperature ( T∼ 60°C), the scattered intensity follows a power law I(q) ∼q-4 in the asymptotic regime, characteristic of two-density media with sharp interfaces, and qmax is found to vary with polymer concentration as qmax∼C0.22. Estimates of the typical sizes give values between 40 A and 200 A. These results provide a strong evidence of a thermally induced microphase separation, which is corroborated by the very sharp increases of the viscosity (over 2 decades) and of the stress relaxation time of the solutions, occurring in the temperature range where the scattering peak is observed. The results are discussed and compared with the theoretical models proposed for weakly charged polyelectrolytes in a poor solvent.

Quantitative Ultrasound techniques are good candidates for the in situ and real-time mechanical characterization of tongue-food-palate system, and thus to improve the understanding of the determinants of texture perception of food. Different model foods (consisting in gels and emulsion filled gels composed of agar and/or gelatin) have been designed for their contrasting properties in terms of texture perceptions. Prior to the feasibility study of a Quantitative Ultrasound method to monitor their mechanical breakdown during a compression, the aim of this study is to determine the respective roles of structure and mechanical properties of the different model foods in the variations of ultrasonic wave properties. Ultrasonic velocity, reflectivity, and attenuation were monitored during the sol-gel transition (from 50°C to 20°C) at 1 MHz in pulse-echo mode, and were confronted to visco-elastic moduli and mass density measurements. The results put in evidence the role of biopolymer concentration (independently ...

The development of non-invasive methods is critical for a better understanding of the biomechanical phenomena involved in the dynamic mechanisms of food texture perception during oral processing. The aim of the present study is to investigate in vitro the potential of a quantitative ultrasound device in order to monitor the mechanical properties of tongue-food interface during a compression. A tongue-palate bio-mimicking set-up was designed, consisting in a traction-compression machine equipped with tongue and palate phantoms. Gels and emulsion filled gels were considered as model foods for their wide ranges of texture properties. Finally, a 1 MHz ultrasonic transducer positioned under the tongue records in real-time the pulse-echo response of the tongue-food-palate system during a compression. The results put in evidence in vitro the potential of tongue-food interface reflexion coefficient to monitor the competitive and collaborative contributions (i) of the tongue-palate system (roughness, lubrication, ...

Objectives 1) To describe autoimmune diseases (AD) in HIV-infected people; and 2) to perform a literature review concerning this issue. Design 52 HIV-infected patients that presented an AD in 14 medical departments in Paris and Ile-de-France area were retrospectively included in this study. Results The ADs were vasculitis (11), immune cytopenias (8), rheumatic diseases (8), lupus (7), sarcoidosis (7), thyroid diseases (6), hepatic diseases (5), and antiphospholipid syndrome (4). Four patients presented 2 ADs. In 5 patients the AD preceded HIV infection, in 14 HIV infection was diagnosed at the same time as the AD and 34 were HIV-infected when they developed an AD. 40 ADs (80%) occurred in patients with a CD4 T lymphocyte count of more than 200/mm 3 . Cases of autoimmune hemolytic anemia occurred only in patients severely immunodepressed. In five patients (a vasculitis case, a sarcoidosis case, three thyroid disease cases) the AD presented as a form of immune restoration inflammatory syndrome (IRIS). Some ADs allowed HIV-infection diagnosis at a stage of moderate immune deficiency (vasculitis, antiphospholipid syndrome, immune thrombocytopenia). 37 patients received immunosuppressant treatments with good tolerance. These results confirm in a large series of patients previous data concerning autoimmune diseases occurrence in HIV-infected people. Conclusion In the HAART era, when HIV-infected people are treated more and more early, autoimmune diseases can occur, mainly at the phase of immunological recovery. HIV infection should not limit immunosuppressant treatment use.

Aim: To analyze HCV care and treatment in HIV-HCV coinfected patients and their evolution between 2006 and2013, in France.Patients and methods: HIV-HCV consecutive seropositive patients were prospectively included in two crosssectional studies from April 3 to 10, 2006 (n=416) and from April 8 to 15, 2013 (n=342). A standard data collection form was used. Results: Patients in 2013 compared to those in 2006 had undetectable HIV viral load and negative HCV viremia more often (82% vs. 69%, and 48% vs. 27%, respectively), with more frequent co-infection by HCV genotype 1 and 4. Liver biopsy was done less frequently (5% vs. 35%). Non-invasive liver damage assessment was done more frequently (42% vs. 22%), using serum biomarkers (37% vs. 67%) or liver-stiffness methods (69% vs. 11%). A sustained virological response to HCV treatment was more frequent (50% vs. 30%). In both surveys, patients who had received HCV treatment compared to those who had never been treated were more often of European origin, had better control of their HIV infection, had more frequent liver damage assessments and were less frequently infected by a genotype 4. Conclusion: In comparison to 2006, more co-infected patients in 2013 had better control of their HIV infection, had liver damage assessment, received HCV treatment and more frequently had a sustained virological response. New anti-HCV combinations with greater efficacy and less toxicity should soon modify the present picture.

International audience; Aggregates – a phenomenon still not understood, as well as pearl necklace-like chain conformation in aqueous solutions of hydrophobic polyelectrolyte are addressed here, using treatment by an organic solvent. The second appear to be at equilibrium in water, the first appear to be metastable, and surprisingly associated with higher zero shear viscosity. The hydrophobic polyelectrolyte is poly(styrene-co-sodium styrene sulfonate), and the solution treatment is to first add to water an organic solvent, THF, which is then evaporated and replaced by the same amount of water. To investigate polyelectrolyte solutions as a function of THF treatment, we use Small Angle Neutron Scattering in the semi-dilute regime, viscosimetry in dilute and semi-dilute regime (unentangled), and osmometry in similar semi-dilute regime (the contribution of the counterions being dominant). First, the structure, namely the scattering from all chains, is characterized by a maximum (" polyelectrolyte peak "). Its position, amplitude and scattered intensity at zero angle depend, at a given sulfonation rate of PSS, on the solvent quality through the added amount of organic solvent (THF). This dependence is very pronounced when the sulfonation rate is low (more hydrophobic polyelectrolyte) and is canceled when the sulfonation rate is high (more hydrophilic polyelectrolyte). Second, the viscosity of the polyelectrolyte solutions decreases with THF treatment for the hydrophobic polyelectrolytes. Third, osmometry shows no noticeable increase of the effective charge with THF treatment. It is proposed that the large scale aggregates, especially in the case of very hydrophobic polyelectrolytes, disappear irreversibly with THF treatment, while the pearl-necklace conformation of the chain remains as in its initial state. Parallel test measurements for a fully hydrophilic polyelectrolyte, poly (sodium-2-acrylamido-2-methylpropane sulfonate) co-(acrylamide): p(AMAMPS) at different sulfonation rates, show no evolution of the structure with THF treatment in the aqueous solution. The same behavior is highlighted by viscosimetry.

cited By 9; International audience; The structural evolution of nanoparticles (NPs) dispersion under uniaxial stretching and extension/retraction deformation cycles above Tg was investigated in model silica/polymethylmethacrylate (PMMA) nanocomposites (PNCs) by a combination of Small Angle X-ray Scattering (SAXS) and Transmission Electronic Microscopy (TEM). The different structure displacements and reorganizations can be quantitatively characterized as a function of elongation ratio, silica volume fraction and NP size. At low NP volume fraction, a rotation/orientation of non-connected aggregates is observed along the stretching direction, while the reinforcement is low and might be limited by the large-scale aggregates. At high volume fraction, the stress-strain curves exhibit three regimes. (i) At low stretching ratio, in the linear deformation regime, reinforcement is driven by the primary network filler structure. (ii) Above a few percent of deformation, a yield is observed and can be associated to the network breakdown as revealed by cyclic extension/retraction experiments. (iii) As a result of this yield, at larger deformation, the stress curve appears as shifted upward with respect to the one of pure polymer. A persistence of this vertical shift (constant value up to large deformation) might be related with SAXS measurements to a non-affine deformation of the NPs network due to new structural arrangements, while in a second case, the decrease of stress to the pure polymer value with increasing deformation is related with observation of affine deformation after the yield. Finally, affinity and non-affinity after yielding are discussed for all the systems according to the strength of the NP-NP interaction. © 2014 Elsevier Ltd. All rights reserved.

Structures induced by a steady shear flow in a semidilute polymer solution of high molecular weight deuterated polystyrene in dioctyl phthalate are investigated. By a combined use of small-angle light scattering (SALS) and small-angle neutron scattering (SANS), we are able to obtain scattering functions of the shear-induced structures over 3 orders of magnitude in wavenumber (q) and 7 orders of magnitude in intensity. The changes in the structures with shear rate (γ) at a given temperature and with temperature at a given γ are explored. At a given temperature, the shear flow induces a structural change in the solution at γ larger than a critical shear rate γc, giving rise to a scattering pattern called “butterfly pattern” in the low q region of SANS, while keeping the same pattern as that in the quiescent state in the q region of SALS. As γ increases, the butterfly patterns evolved not only in the low q region of SANS but also in the q region of SALS. This indicates that the shear-induced structures ...

The temperature dependence of lysozyme solubility has been measured in light and heavy water in KCl and in NaNO3 at pH=4.5. The solubilities have been determined with the static light device previously developed to determine the temperature dependence of lysozyme solubility in NaCl. In the present work, we show that the solubility curves in light and heavy water are shifted by 7.2°C in both KCl and NaNO3, as previously observed with NaCl. This temperature shift is the same, which is found between the temperature dependence of density and of other physical quantities of heavy and light water. These new results evidence a general trend of how structural aspects of bulk water can have a profound impact on the properties of biological systems.

We have used helium-3 nuclear reaction analysis to measure the interdiffusion of linear polystyrene into a film of crosslinked polystyrene and the intradiffusion of polystyrene in polystyrene networks. The interdiffusion is compared with that predicted from the Kramer-Sillescu theory, and is found to be considerably faster. This is attributed to the relaxation of inhomogeneities in the network. The molecular weight and crosslinking dependence of the intradiffusion coefficients of free polystyrene chains trapped inside networks is discussed in terms of the simple tube model and provides reasonably good agreement with that predicted from reptation theory.

We have used neutron reflectometry and carbon and neon forward recoil spectrometry to measure the surface segregation of deuterated polystyrene from a hydrogenous polystyrene network. We find that when the linear polymer is of a high molecular weight (~600 000), the surface segregated profile can be predicted by mean field theory. In these systems the segregation is a rather slow function of time, reflecting the large number of entanglements in such crosslinked mixtures. When the deuterated polystyrene is of a lower molecular weight (~100 000), the surface segregated layer does not evolve monotonically with time but the shape of the profile can be predicted by mean-field theory. However, when the network is significantly crosslinked, the linear polymer is expelled from the network.

We report preliminary simulations of anisotropic scattering from aggregates of small hard spherical particles embedded in an elastic polymer matrix, using simple geometrical methods. First we build several types of aggregates in three dimensions: crystalline, amorphous compact, fractals, of different numbers of particles and varying polydispersity. We then turn to the spectra of deformed samples simulated in two dimensions. We impose an affine displacement inside the matrix to the fillers, which can be isolated particles or small aggregates, and account for the collisions which arise due to lateral shrinking of the material. The two-dimensional scattering spectra are shown and discussed. They reproduce experimentally observed isointensity curves: ellipses, banana-shaped maxima and splitting of these maxima in four spots. Finally, we explore the consequences of the reduction to two dimensions via statistics of the number of collisions. It is found that even if collisions are more important in 3 dimensions, the behavior is qualitatively similar in two and three dimensions.

This article reports a study of the chain conformation in thin films of amorphous polymer prepared by spin coating. Polystyrene chains of two molecular weights Mw, 230 000 and 660 000, are confined in layers of thickness equal to either 1000 A, thus greater than their unperturbed radii of gyration Rg, or 100 A, thus smaller than Rg. The form factor of the chain inside the layer is measured by small-angle neutron scattering. Changes of the scattering are observed as a function of the film thickness in the intermediate scattering vector range. We analyze the data in the frame of the wormlike model. In the 1000 A films, the chain has the same Gaussian conformation as in the bulk. In the films of 100 A, the persistence length of the chain is increased (compared to 9.2 A the value in the bulk) up to 45 A, for both Mw values. However, the corresponding scattering intensity is higher than expected for such an extended chain.

Objective To estimate the change in survival of patients with AIDS-related progressive multifocal leukoencephalopathy (PML), in relation to the introduction of protease inhibitors (PI). Design The French Hospital Database on HIV (FHDH) is a prospective cohort of 70 224 HIV-infected subjects. This study included the patients diagnosed with PML between 1 July 1995 and 30 June 1997. PML diagnosis was both presumptive and confirmed. We compared the survival probability according to the diagnosis period (period 1 or 2, before or after introduction of PI in France on 1 April 1996). Cox's model was used to calculate the relative hazards of death according to the antiretroviral regimen. Results The study included 246 patients, 109 diagnosed during period 1 and 137 during period 2. In all, 131 patients received an antiretroviral combination that included PI. By 31 December 1997, a total of 131 deaths had been reported. The probability of survival at 6 months for patients from period 2 was nearly twice as high as for patients from period 1 (60.5 versus 34.5%). In comparison with patients receiving no treatment, the risk of death in patients on combination therapy not including PI was reduced by 38% [relative hazard (RH) 0.62, 95% confidence interval (CI) (0.41; 0.95), P = 0.026] and in patients on combination therapy with PI, by 63% [RH 0.37, 95% CI (0.22; 0.64), P = 0.0004]. Conclusion This study of a large cohort of patients diagnosed with PML (n = 246), provides evidence that a combination antiretroviral regimen, especially one including PI, confers marked survival benefits.

We use small angle neutron scattering to study the effect of shear on a polymer solution (polystyrene, PS, in dioctyl phthalate, DOP) being in the entangled part of the semidilute regime, in a larg...