Article
Chemistry, Multidisciplinary
Roman Stano, Jan Smrek, Christos N. Likos
Summary: Concentrated solutions of semiflexible polyelectrolyte ring polymers can form nanoscopic cylindrical stacks, and the morphology and dynamics of these clusters can be controlled by the presence of counterions. Addition of trivalent ions stabilizes the formation of clusters, while monovalent ions affect the density of the clusters.
Article
Polymer Science
Wenduo Chen, Shaonan Wei
Summary: This study utilized Langevin Dynamics Simulations to investigate the compression and relaxation processes of confined ring polymers in a nanochannel. The findings revealed that ring polymers exhibit complex deformations under different levels of confinement, with weakly confined polymers compressed into condensed blobs and strongly confined polymers undergoing deformations from double helix to collapsed states. During relaxation, weakly confined rings return to their initial states, while strongly confined rings extend from compacted states to randomly folded states due to interpenetrated and self-entangled structures formed during compression.
Article
Astronomy & Astrophysics
Minyong Guo, Zhen Zhong, Jinguang Wang, Sijie Gao
Summary: In this article, it is argued that ultracompact objects with light rings but no horizons may be unstable. The quasiblack hole solutions, which are horizonless spacetimes, were studied to test this conjecture. A critical parameter at which the light rings appear was identified, and the quasinormal modes of the quasiblack holes were calculated. The results showed that long-lived modes exist within the range of light rings, indicating the instability of horizonless spacetimes with light rings. This work provides strong evidence that light rings could be directly observed as black holes.
Article
Engineering, Electrical & Electronic
Ze Zhang, Zilong Wang, Juntao Yu, Dunbo Yu, Yang Luo, Wenlong Yan, Yuanfei Yang, Tengfei Hu, Li Wang
Summary: This paper compares the application of two different sinusoidal magnetization methods of a bonded magnetic ring in a permanent magnet motor. The results show that the performance of the two methods is similar, and the two methods have their own advantages. This paper provides some reference value for the selection of sinusoidal magnetization mode of a bonded magnetic ring.
Article
Polymer Science
Luigi Grassia, Alberto D'Amore
Summary: A new method for calculating the retardation spectra of linear viscoelastic materials is presented, revealing the relationship between shear response and volumetric bulk response. The study shows that the shear segmental contribution is narrower than the volumetric bulk response.
Article
Multidisciplinary Sciences
Birte Riechers, Lisa A. Roed, Saeed Mehri, Trond S. Ingebrigtsen, Tina Hecksher, Jeppe C. Dyre, Kristine Niss
Summary: The noncrystalline glassy state of matter is important in materials science and offers unique properties. However, it undergoes physical aging due to being out of equilibrium. The existence of a material time is validated and physical aging can be predicted using fluctuation-dissipation theorem and computer simulations.
Article
Astronomy & Astrophysics
A. James Friedson, Marzia Parisi, Lyra Cao, Xiaohan Xue Pew, Leon Ding, Katherine Broad
Summary: This study calculates the quasi-toroidal normal modes of Saturn and proposes that these oscillations are responsible for exciting slowly propagating density waves observed in the C ring. The results suggest a potential source of new constraints on the planet's internal stratification. The significance of the instability mechanism and further study of these modes are still open questions. Evaluation: 7/10.
Article
Plant Sciences
Irina Sviderskaya, Eugene A. Vaganov, Marina Fonti, Patrick Fonti
Summary: The study utilizes isometric scaling between tracheids and pit morphology to upscale these properties to the tree-ring level in conifers. Results indicate that natural inter- and intra-ring anatomical variations have a substantial impact on the tree's hydraulic properties. This approach provides a novel way to investigate xylem structure-function relationships across time and environmental conditions.
JOURNAL OF EXPERIMENTAL BOTANY
(2021)
Article
Plant Sciences
Gonzalo Perez-de-Lis, Cyrille B. K. Rathgeber, Laura Fernandez-de-Una, Stephane Ponton
Summary: The study examined the spatio-temporal relationship in tree rings during cell enlargement and wall thickening processes, finding that wall thickening progresses more rapidly than enlargement. Increasing the number of sectors above a certain threshold has limited effect on time resolution, with overlapping sector formation reducing synchronicity and stability, especially in narrow rings and during wall thickening.
Article
Cardiac & Cardiovascular Systems
Eilon Ram, Yael Peled, Ehud Karni, Efrat Mazor Dray, Hillit Cohen, Leonid Sternik, Ehud Raanani
Summary: The type of ring used in tricuspid annuloplasty may affect outcomes. This study compared the results of using three-dimensional semi-rigid rings and open simple-band annuloplasty, and found that the two types of rings had similar outcomes.
EUROPEAN JOURNAL OF CARDIO-THORACIC SURGERY
(2022)
Article
Chemistry, Physical
Subaru Konishi, Junsu Park, Osamu Urakawa, Motofumi Osaki, Hiroyasu Yamaguchi, Akira Harada, Tadashi Inoue, Go Matsuba, Yoshinori Takashima
Summary: This study investigated the relationship between molecular mobility and mechanical toughness of supramolecular hydrogels with different kinetic reversible cross-links. It was found that hydrogels combining fast and slow reversible cross-links showed increased toughness.
Article
Polymer Science
Takahiro Murashima, Katsumi Hagita, Toshihiro Kawakatsu
Summary: Coarse-grained molecular dynamics simulations were used to analyze blends of multicyclic and linear polymers under biaxial elongational flow. The blends exhibited an overshoot behavior in the normal stress difference, with multicyclic/linear blends showing a steeper overshoot compared to monocyclic/linear blends. The origin of the overshoot was found to be a topological transition mechanism in the multicyclic chains, which resulted in a drastic change in the stress of the rings.
Article
Environmental Sciences
Xiaohu Xiong, Weijian Zhou, Xiaolin Hou, Peng Cheng, Hua Du, Xue Zhao, Shugang Wu, Yaoyao Hou, Xuefeng Lu, Yunchong Fu
Summary: The research reconstructs a Delta(CO2)-C-14 time series from 1957 to 2015 using Qinghai spruce tree rings collected from Huangzhong. The results show that the Delta C-14 values in Huangzhong were generally higher than the contemporaneous average level in the mid-high latitudes of the Northern Hemisphere.
Article
Polymer Science
Yu-Chao Li, Zong-Pei Wu, Ze-Hao Zong, Xue-Zheng Cao
Summary: This study found that segments of a stiff nanoring (SNR) exhibit more facilitated subdiffusion than those belonging to a flexible counterpart, while the whole SNR is more suppressed by its surroundings. Adding SNRs contributes to achieving sol and gel-like characteristics at high and low shearing frequencies, respectively. This study suggests the promising prospect of exploiting SNRs to concurrently strengthen and toughen target polymer nanocomposites.
Article
Polymer Science
Xue-Zheng Cao, Yu -Chao Li, Zong-Pei Wu, Ze-Hao Zong
Summary: The study shows that segments of a stiff nanoring (SNR) have more facilitated subdiffusion and the whole SNR is more suppressed when immersed in a polymer melt matrix. Adding SNRs contributes to achieving sol and gel-like characteristics at high and low shearing frequencies, respectively. This study suggests the promising prospect of using SNRs to strengthen and toughen polymer nanocomposites.
Article
Mechanics
Claudia Dessi, Salvatore Coppola, Dimitris Vlassopoulos
Summary: Dynamic mechanical oscillatory shear measurements with torsional rectangular geometry are commonly used to determine mechanical properties of soft solid materials. The technique avoids slip effects and is particularly suitable for testing stiff elastomers, but requires a clamping system which may lead to increased dynamic moduli. Different torsion models are tested to describe the constrained warping effect in industrial rubber, with a modified Vlasov's model shown to provide realistic predictions over a wider parameter range.
JOURNAL OF RHEOLOGY
(2021)
Editorial Material
Physics, Condensed Matter
Raffaele Pastore, Giuseppe Mensitieri, Dimitris Vlassopoulos, Francesco Greco
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Mechanics
Celine Hannecart, Taisir Shahid, Dimitris Vlassopoulos, Filip Oosterlinck, Christian Clasen, Evelyne van Ruymbeke
Summary: A new alternative approach is proposed to explain the peculiar behavior of polymer chains under uniaxial extensional flow, taking into account chain stretching, orientation, and a rate-dependent blob picture. This method introduces an additional parameter for describing stretch relaxation time, but results are in good agreement with experimental observations.
JOURNAL OF RHEOLOGY
(2022)
Article
Mechanics
D. Parisi, D. Vlassopoulos, H. Kriegs, J. K. G. Dhont, K. Kang
Summary: Soft glasses of colloidal rods with orientational domains exhibit inhomogeneous flow profiles, including fracture, plug flow, and gradient shear-banding. The observed gradient shear-banding is mainly attributed to the strong shear thinning behavior of the material inside the domains. Both texture stress and domain-interior stress significantly contribute to the gradient shear-banding transition at high concentrations, while domain coalescence reduces texture stress at low concentrations.
JOURNAL OF RHEOLOGY
(2022)
Article
Polymer Science
Nikolaos A. Burger, Gaelle Pembouong, Laurent Bouteiller, Dimitris Vlassopoulos, Benoit Loppinet
Summary: This study revisits the equilibrium phase diagram of the model supramolecular polymer EHUT in nonpolar solvents and uncovers a richer behavior with four distinct regimes. By combining rheology and microrheology, the complete dynamic phase diagram of EHUT in dodecane is established, revealing three dynamic states of the tube structure at different concentrations. The findings provide insights into investigating other supramolecular polymers with tunable rheology and understanding one-dimensional self-assembled structures.
Article
Chemistry, Physical
Nikolaos A. Burger, Gerhard Meier, Laurent Bouteiller, Benoit Loppinet, Dimitris Vlassopoulos
Summary: The study presents a methodology for investigating the linear viscoelastic properties of complex fluids at elevated pressures, showing that increased pressure affects the terminal relaxation process but has a minimal impact on viscosity and entanglement. The viscoelastic properties exhibit similar concentration dependencies under different pressures.
JOURNAL OF PHYSICAL CHEMISTRY B
(2022)
Article
Mechanics
Consiglia Carillo, Stephan Zoellner, Evelyne van Ruymbeke, Dimitris Vlassopoulos
Summary: This study investigates the linear viscoelastic properties of industrial pressure sensitive adhesives with double networks, analyzing the effects of different compositions on their viscoelastic spectra. By comparing the dynamics of double networks with individual responses of polymeric components without crosslinks and single networks, the contributions to relaxation mechanisms are quantified. The research provides insights into tuning material parameters for desired viscoelastic behavior.
JOURNAL OF RHEOLOGY
(2022)
Article
Mechanics
Yanzhao Li, Christina Pyromali, Flanco Zhuge, Charles-Andre Fustin, Jean-Francois Gohy, Dimitris Vlassopoulos, Evelyne van Ruymbeke
Summary: This study investigates the linear viscoelastic properties of polymeric networks formed by metal-ligand cross-links with different lifetimes, revealing unexpected dynamics and proposing a model to quantify the transient dynamics of the network.
JOURNAL OF RHEOLOGY
(2022)
Article
Mechanics
Christina Pyromali, Yanzhao Li, Flanco Zhuge, Charles-Andre Fustin, Evelyne van Ruymbeke, Dimitris Vlassopoulos
Summary: This study presents a systematic experimental investigation of the shear rheology of metallosupramolecular assemblies, focusing on the effects of concentration and strength of physical bonds on nonlinear response. The results reveal that increasing shear strain leads to stronger shear thinning behavior, and double dynamics networks exhibit enhanced mechanical coherence and strain accumulation compared to single-ion counterparts. The failure of the Cox-Merz rule is observed with increased association strength.
JOURNAL OF RHEOLOGY
(2022)
Article
Polymer Science
Yanlin Shi, Sung-Po R. Chen, George Fragkiadakis, Daniele Parisi, Virgil Percec, Dimitris Vlassopoulos, Michael J. Monteiro
Summary: The shape, breadth, and average molecular weight of the overall molecular weight distribution (MWD) are important for determining polymer properties. Traditional methods can only achieve desired Gaussian distribution through complex modeling, while living radical polymerization provides a simpler route. Blending low-reactive RAFT agents allows the construction of square, slanted, and chair-like MWDs, providing control over MWD shape and breadth. This blending method overcomes difficulties in producing unusual MWDs and offers a general synthetic strategy for studying structure-property relationships of polymers.
Article
Mechanics
Emmanouil Vereroudakis, Nathan Van Zee, E. W. Meijer, Dimitris Vlassopoulos
Summary: We investigated the behavior of a supramolecular polymer under repeated shear-startup runs. This test, proposed 50 years ago, is used to measure disentanglement kinetics in linear polymers. The recovery time was found to mainly reflect chain reorientation, but for the supramolecular polymer in this study, it was rate independent. This difference is attributed to the different mechanism of stress relaxation involving bond breaking/recombination and reptation processes. The repeated shear-startup protocol can serve as an indicator of polymer signatures and a tool to evaluate stress relaxation models.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2023)
Article
Mechanics
Daniele Parisi, Emmanouil Vereroudakis, Yuichi Masubuchi, Giovanni Ianniruberto, Giuseppe Marrucci, Dimitris Vlassopoulos
Summary: Evidence from state-of-the-art experiments, modeling and simulations suggests the existence of an undershoot in fast flows of entangled polymers, following the overshoot during shear startup. Blending two entangled homopolymers at different compositions affects the undershoot, possibly by changing the distribution of relaxation times. By modifying the tube-based model and using simulations, we demonstrate how the undershoot depends on the blend composition.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2023)
Article
Polymer Science
Daniele Parisi, Domenico Truzzolillo, Ali H. Slim, Phillippe Dieudonne-George, Suresh Narayanan, Jacinta C. Conrad, Vishnu D. Deepak, Mario Gauthier, Dimitris Vlassopoulos
Summary: Liquid mixtures of colloidal particles and non-adsorbing linear homopolymers can undergo gelation transition due to polymer-mediated depletion forces. Addition of linear polymers to suspensions of soft colloids of the same size results in a liquid-togel-to-re-entrant liquid transition. This behavior is explained by the interplay between depletion interactions, colloidal deswelling, and the suppression of depletion efficiency with increased polymer concentration.
Article
Mechanics
Stelios Alexandris, Daniel Ashkenazi, Jan Vermant, Dimitris Vlassopoulos, Moshe Gottlieb
Summary: When surface-active molecules or particles assemble at fluid-fluid interfaces, the rheological properties of these interfaces become complex, which plays an important role in processes involving interface flow and deformation. However, measuring interfacial rheological properties of polymers at the air-water interface is challenging due to various factors such as weak interactions with the water subphase, polymer backbone conformation, glass transition of the interfacial layer, and memory effects. In this study, we conducted systematic rheological measurements of polymer-laden interfaces and compared the results obtained by different types of rheometers. We found that the reproducibility and comparability of the rheological data were poor, mainly due to differences in layer preparation methods. Therefore, it is crucial to control the surface pressure and use a specific method to prepare the layers in order to obtain reliable and meaningful rheological data.
JOURNAL OF RHEOLOGY
(2023)
Article
Mechanics
Dimitrios G. Tsalikis, Vlasis G. Mavrantzas, Sotiris E. Pratsinis
Summary: The mechanics and dynamics of molecular collisions in air were investigated using atomistic molecular dynamics simulations. The study found that due to the rotational motion and non-spherical shape of molecules, complex trajectories and multi-molecular collisions occur. By filtering out spurious collisions, the average free path of air was determined to be 38.5 +/- 1nm, which is 43% smaller than the widely accepted value.