Non-Gaussian curvature distribution of actin-propelled biomimetric colloid trajectories

We analyze the motion of colloids propelled by a comet-like tail of polymerizing actin filaments. The curvature of the particle trajectories deviates strongly from a Gaussian distribution, implying that the underlying microscopic processes are fluctuating in a non-independent manner. Trajectories for beads of different size all showed the same non-Gaussian behavior, while the mean curvature decreased weakly with size. A stochastic simulation that includes nucleation, force-dependent dissociation, growth, and capping of filaments, shows that the non-Gaussian curvature distribution can be explained by a positive feedback mechanism in which attached chains under higher tension are more likely to sna

Elongated particles discharged with a conveyor belt in a two-dimensional silo

The flow of elliptical particles out of a 2-dimensional silo when extracted with a conveyor belt is analyzed experimentally. The conveyor belt - placed directly below the silo outlet - reduces the flow rate, increases the size of the stagnant zone, and it has a very strong influence on the relative velocity fluctuations as they strongly increase everywhere in the silo with decreasing belt speed. In other words, instead of slower but smooth flow, flow reduction by belt leads to intermittent flow. Interestingly, we show that this intermittency correlates with a strong reduction of the orientational order of the particles at the orifice region. Moreover, we observe that the average orientation of the grains passing through the outlet is modified when they are extracted with the belt, a feature that becomes more evident for large orifices.Comment: 11 pages, 11 figures, final version published in Phys. Rev.

Temperature-Responsive Polyelectrolyte Complexes for Bio-Inspired Underwater Adhesives

Adhesive proteins of marine organisms contain significant amounts of hydrophobic amino acids. Therefore, inter- and intramolecular hydrophobic interactions are expected to play an important role in both adhesion and cohesion. Here, we mimic the hydrophobicity of adhesive proteins by using temperature-responsive polyelectrolyte complexes (TERPOCs) with a high poly(N-isopropylacrylamide) (PNIPAM) content. Upon mixing aqueous solutions of PNIPAM-b-poly(acrylic acid)-b-PNIPAM and poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA), complexation between the oppositely charged polyelectrolytes occurs. At low temperatures, complex coacervate core micelles (C3Ms) with a PNIPAM corona are formed, and upon a temperature increase, the solution turns into a hydrogel by the formation of a network of hydrophobic PNIPAM domains. Consequently, an abrupt increase in viscosity is observed upon heating which facilitates injectability of the adhesive. The gelation temperature, Tgel, and (adhesive) strength of the TERPOC can be adjusted by altering the salt and polymer concentration, which changes the balance between the electrostatic and hydrophobic interactions. Despite the importance of hydrophobic groups in strong underwater adhesives, we conclude that TERPOCs with a high PNIPAM content (70 wt%) are unstable due to water release. Consequently, there is a limited amount of hydrophobic groups that can be inserted in this type of systems. Nevertheless, TERPOCs show promising and tunable properties for application as injectable underwater adhesives, for example in biomedical applications

Multiple shear-banding transitions in a supramolecular polymer solution

We report on the nonlinear rheology of a reversible supramolecular polymer based on hydrogen bonding. The coupling between the flow-induced chain alignment and breakage and recombination of bonds between monomers leads to a very unusual flow behavior. Measured velocity profiles indicate three different shear-banding regimes upon increasing shear rate, each with different characteristics. While the first of these regimes has features of a mechanical instability, the second shear-banding regime is related to a shear-induced phase separation and the appearance of birefringent textures. The shear-induced phase itself becomes unstable at very high shear rates, giving rise to a third banding regime

68Ga-NODAGA-RGDyK PET/CT Imaging in Esophageal Cancer: First-in-Human Imaging.

Ga-NODAGA-RGDyK(cyclic) and FDG PET/CT were performed in a 39-year-old man for the work-up of a moderately differentiated carcinoma of the gastro-esophageal junction within a clinical study protocol. Although FDG PET images showed intense, diffuse hypermetabolic lesion activity, NODAGA-RGDyK illustrated the neo-angiogenesis process with tracer uptake clearly localized in non-FDG-avid perilesional structures. Neo-angiogenesis is characterized by ανβ3 integrin expression at the lesion surface of newly formed vessels. This case supports evidence that angiogenesis imaging might therefore be a crucial step in early disease identification and localization, metastatization potential, and in monitoring the efficacy of antiangiogenic therapies

Linking slow dynamics and microscopic connectivity in dense suspensions of charged colloids

The quest to unravel the nature of the glass transition, where the viscosity of a liquid increases by many orders of magnitude, while its static structure remains largely unaffected, remains unresolved. While various structural and dynamical precursors to vitrification have been identified, a predictive and quantitative description of how subtle changes at the microscopic scale give rise to the steep growth in macroscopic viscosity is missing. It was recently proposed that the presence of long-lived bonded structures within the liquid may provide the long-sought connection between local structure and global dynamics. Here we directly observe and quantify the connectivity dynamics in liquids of charged colloids en route to vitrification using three-dimensional confocal microscopy. We determine the dynamic structure from the real-space van Hove correlation function and from the particle trajectories, providing upper and lower bounds on connectivity dynamics. Based on these data, we extend Dyre's model for the glass transition to account for particle-level structural dynamics; this results in a microscopic expression for the slowing down of relaxations in the liquid that is in quantitative agreement with our experiments. These results indicate how vitrification may be understood as a dynamical connectivity transition with features that are strongly reminiscent of rigidity percolation scenarios

Lack of phylogeographic structure in the freshwater cyanobacterium <i>Microcystis aeruginosa</i> suggests global dispersal

Background: Free-living microorganisms have long been assumed to have ubiquitous distributions with little biogeographic signature because they typically exhibit high dispersal potential and large population sizes. However, molecular data provide contrasting results and it is far from clear to what extent dispersal limitation determines geographicstructuring of microbial populations. We aimed to determine biogeographical patterns of the bloom-forming freshwatercyanobacterium Microcystis aeruginosa. Being widely distributed on a global scale but patchily on a regional scale, this prokaryote is an ideal model organism to study microbial dispersal and biogeography.Methodology/Principal Findings: The phylogeography of M. aeruginosa was studied based on a dataset of 311 rDNAinternal transcribed spacer (ITS) sequences sampled from six continents. Richness of ITS sequences was high (239 ITS typeswere detected). Genetic divergence among ITS types averaged 4% (maximum pairwise divergence was 13%). Preliminary analyses revealed nearly completely unresolved phylogenetic relationships and a lack of genetic structure among all sequences due to extensive homoplasy at multiple hypervariable sites. After correcting for this, still no clear phylogeographic structure was detected, and no pattern of isolation by distance was found on a global scale. Concomitantly, genetic differentiation among continents was marginal, whereas variation within continents was high and was mostly shared with all other continents. Similarly, no genetic structure across climate zones was detected.Conclusions/Significance: The high overall diversity and wide global distribution of common ITS types in combination with the lack of phylogeographic structure suggest that intercontinental dispersal of M. aeruginosa ITS types is not rare, and that this species might have a truly cosmopolitan distribution

Signature of survival: a ¹⁸F-FDG PET based whole-liver radiomic analysis predicts survival after ⁹⁰Y-TARE for hepatocellular carcinoma.

To generate a predictive whole-liver radiomics scoring system for progression-free survival (PFS) and overall survival (OS) in patients undergoing transarterial radioembolization using Yttrium-90 ( &lt;sup&gt;90&lt;/sup&gt; Y-TARE) for unresectable hepatocellular carcinoma (uHCC). The generated pPET-RadScores were significantly correlated with survival for PFS (median of 11.4 mo [95% confidence interval CI: 6.3-16.5 mo] in low-risk group [PFS-pPET-RadScore &lt; 0.09] vs. 4.0 mo [95% CI: 2.3-5.7 mo] in high-risk group [PFS-pPET-RadScore &gt; 0.09]; &lt;i&gt;P&lt;/i&gt; = 0.0004) and OS (median of 20.3 mo [95% CI: 5.7-35 mo] in low-risk group [OS-pPET-RadScore &lt; 0.11] vs. 7.7 mo [95% CI: 6.0-9.5 mo] in high-risk group [OS-pPET-RadScore &gt; 0.11]; &lt;i&gt;P&lt;/i&gt; = 0.007). The multivariate analysis confirmed PFS-pPET-RadScore ( &lt;i&gt;P&lt;/i&gt; = 0.006) and OS-pPET-RadScore ( &lt;i&gt;P&lt;/i&gt; = 0.001) as independent negative predictors. Pretreatment &lt;sup&gt;18&lt;/sup&gt; F-FDG PET whole-liver radiomics signature appears as an independent negative predictor for PFS and OS in patients undergoing &lt;sup&gt;90&lt;/sup&gt; Y-TARE for uHCC. Pretreatment &lt;sup&gt;18&lt;/sup&gt; F-FDG PET of 47 consecutive patients undergoing &lt;sup&gt;90&lt;/sup&gt; Y-TARE for uHCC (31 resin spheres, 16 glass spheres) were retrospectively analyzed. For each patient, based on PET radiomics signature from whole-liver semi-automatic segmentation, PFS and OS predictive PET-radiomics scores (pPET-RadScores) were obtained using LASSO Cox regression. Using X-tile software, the optimal score to predict PFS (PFS-pPET-RadScore) and OS (OS-pPET-RadScore) served as cutoff to separate high and low-risk patients. Survival curves were estimated using the Kaplan-Meier method. The prognostic value of PFS and OS-pPET-RadScore, Barcelona-Clinic Liver Cancer staging system and serum alpha-fetoprotein level was analyzed to predict PFS and OS in multivariate analysis

Voxel-based 18F-FET PET segmentation and automatic clustering of tumor voxels: A significant association with IDH1 mutation status and survival in patients with gliomas.

Aim was to develop a full automatic clustering approach of the time-activity curves (TAC) from dynamic 18F-FET PET and evaluate its association with IDH1 mutation status and survival in patients with gliomas. Thirty-seven patients (mean age: 45±13 y) with newly diagnosed gliomas and dynamic 18F-FET PET before any histopathologic investigation or treatment were retrospectively included. Each dynamic 18F-FET PET was realigned to the first image and spatially normalized in the Montreal Neurological Institute template. A tumor mask was semi-automatically generated from Z-score maps. Each brain tumor voxel was clustered in one of the 3 following centroids using dynamic time warping and k-means clustering (centroid #1: slowly increasing slope; centroid #2: rapidly increasing followed by slowly decreasing slope; and centroid #3: rapidly increasing followed by rapidly decreasing slope). The percentage of each dynamic 18F-FET TAC within tumors and other conventional 18F-FET PET parameters (maximum and mean tumor-to-brain ratios [TBRmax and TBRmean], time-to-peak [TTP] and slope) was compared between wild-type and IDH1 mutant tumors. Their prognostic value was assessed in terms of progression free-survival (PFS) and overall survival (OS) by Kaplan-Meier estimates. Twenty patients were IDH1 wild-type and 17 IDH1 mutant. Higher percentage of centroid #1 and centroid #3 within tumors were positively (P = 0.016) and negatively (P = 0.01) correlated with IDH1 mutated status. Also, TBRmax, TBRmean, TTP, and slope discriminated significantly between tumors with and without IDH1 mutation (P range 0.01 to 0.04). Progression occurred in 22 patients (59%) at a median of 13.1 months (7.6-37.6 months) and 13 patients (35%) died from tumor progression. Patients with a percentage of centroid #1 &gt; 90% had a longer survival compared with those with a percentage of centroid #1 &lt; 90% (P = 0.003 for PFS and P = 0.028 for OS). This remained significant after stratification on IDH1 mutation status (P = 0.029 for PFS and P = 0.034 for OS). Compared to other conventional 18F-FET PET parameters, TTP and slope were associated with PFS and OS (P range 0.009 to 0.04). Based on dynamic 18F-FET PET acquisition, we developed a full automatic clustering approach of TAC which appears to be a valuable noninvasive diagnostic and prognostic marker in patients with gliomas