We reveal a unique effect in which the ultrasonic transmission efficiency from the air to the liquid is significantly enhanced by the liquid surface concavity induced by ultrasound. The surface concavity acts as a special geometry-controllable transducer to transmit ultrasound into the liquid, where the sound transmission efficiency exhibits a relationship with the concavity depth: τ ∼ d2.
Control over spatial concentration fields represents a fundamental challenge in designing synthetic biological systems and programmable soft materials. While nature creates morphogen gradients that orchestrate complex developmental processes, synthetic approaches have largely relied on empirical optimization and computationally intensive simulations. Here, we present an analytical framework for steady-state concentration fields generated by finite-sized localized sources in diffusion–degradation systems and derive closed-form solutions for one-, two-, and three-dimensional geometries. By expressing these solutions in dimensionless form, we show that gradient steepness and spatial structure are organized by the Thiele modulus, which captures the competition between diffusion and degradation length scales. The analysis reveals distinct design regimes: in degradation-dominated systems, gradient shape is governed by exponential decay and becomes dimension-independent, whereas in diffusion-dominated systems, gradient magnitude and extent follow dimension-dependent power-law scaling. Building on these results, we introduce a quantitative design strategy that uses threshold-based criteria to program concentration ranges by tuning physically accessible parameters, most directly the production rate, while holding transport and degradation properties fixed. Comparisons with numerical solutions and reported experimental systems demonstrate consistency with the predicted scaling behavior. Together, this work provides a generalizable and physically transparent framework for designing steady-state concentration fields in synthetic biological and soft matter systems, enabling predictive control of gradient-mediated organization without reliance on extensive numerical optimization.
The rational functionalization of pillar[n]arenes enables unprecedented properties, establishing it as a pivotal strategy for constructing advanced functional materials. In this study, we synthesized a series of asymmetrically functionalized pillar[5]arene derivatives H1, H2, and H3, whose molecules were terminated with ester, carboxylate, and carboxylate groups, respectively. The morphological study of these molecular assemblies indicated that different molecular termini significantly influence self-assembly of nanostructures, which leads to the formation of nanospheres, nanosheets, and cross-linked nanomicelles, respectively. Furthermore, the host–guest complexes H2G and H3G, formed by molecule G containing a tetraphenylethylene (TPE) core and molecules H2–3, self-assemble into dendritic and feather-like aggregates in aqueous solution, respectively. The experimental results revealed that the intermolecular interaction of the rigid building block, the hydrophilic/hydrophobic effect, and the structure of the terminal groups synergistically affect the morphology of the supramolecular assemblies. Interestingly, a pH-sensitive reversible morphological conversion between H2G and H3G was established, which could be utilized for fluorescence information encryption. The findings of this study provide not only a new design strategy for functionalized pillar[5]arenes but also a novel approach for constructing advanced stimulus-responsive supramolecular materials.
Forming giant aggregates with surfactants in nonaqueous solvents is typically challenging due to weak solvophobic interactions. In this study, a series of phenylalanine-based surfactants—alkyl phenylalanine amide oxides (Cn-Phe-AO, n = 12, 14, and 16)—were synthesized. These surfactants independently induced gelation of glycerol at remarkably low concentrations of 22.5, 12.7, and 10 mM, respectively, compared with other glycerol systems. The zero-shear viscosity of a 10 mM C16-Phe-AO glycerol solution reached 10 501 Pa s. Cryogenic transmission electron microscopy (cryo-TEM) and circular dichroism (CD) confirmed the formation of left-handed helical structures, which account for the pronounced viscoelasticity of the glycerol solutions. The phenylalanine residue promotes regular molecular packing within the aggregates, enabling the formation of robust helical assemblies in glycerol that maintain a densely entangled network. Comparative analysis of aggregation in glycerol and 1,3-propanediol revealed that the hydrogen-bonding capability of the solvent is the primary driving force for the development of elongated micellar aggregates. This study establishes a model system for gelled glycerol solutions with minimal surfactants and offers new insights into molecular self-assembly in nonaqueous media.
We investigate sample-to-sample fluctuations of the shear modulus in ensembles of particle packings near the jamming transition. Unlike the average modulus, which exhibits distinct scaling behaviours depending on the interparticle potential, the fluctuations obey a critical exponent that is independent of the potential. Furthermore, this scaling behaviour has been confirmed in two-dimensional packings, indicating that it holds regardless of spatial dimension. Using this scaling law, we discuss the relationship predicted by heterogeneous-elasticity theory between elastic-modulus fluctuations and the Rayleigh scattering of sound waves across different pressures. Our numerical results provide a useful foundation for developing a unified theoretical description of the jamming critical phenomenon.
A new homologous series of mesogenic compounds with nearly linear mesogenic cores was studied, and it showed a strong discrimination between nematic and smectic phases with respect to the length of the terminal chain. For short homologues a ferroelectric nematic, NF and a heliconical nematic, NTBF phases were observed, while for longer ones they were replaced with ferroelectric smectic AF and CF phases. The n = 3 homologue exhibits a unique sequence of SmCF and its heliconical analogue SmCHP. Replacing an alkyne linkage in the mesogenic core with an alkene one favoured smectic phases and led to the appearance of a modulated-type SmAAF phase.
The application of an external field often renders empirical criteria for identifying liquid–gas phase transitions ambiguous. Here, we demonstrate that the finite-size scaling of the density profile provides a definitive criterion to distinguish liquid–gas coexistence from a single fluid phase in field-confined systems. Our scaling method collapses the density profiles of different system sizes onto a single master curve for a one-phase system, while causing the profiles to intersect at the interface in a two-phase system. We validate this theoretical proposal through experiments and simulations of two model systems: colloidal suspensions under gravity and two-dimensional complex plasmas confined by a central potential. Our method is broadly applicable for detecting liquid–gas phase transitions in laboratory systems where external fields are inherent.
This study investigates the complex molecular dynamics of discotic liquid crystals (DLCs) by comparing two structurally similar compounds: hexakis(hepta-alkanoyloxy)triphenylene (HOT6) and hexakis(hexa-alkyloxy)triphenylene (HAT6) having the same triphenyl core and the same length of the alkyl side chain. The difference of both materials is that the alkyl chain is linked by an oxygen bridge to the triphenylene core for HAT6 and by a ester group for HOT6. Using a combination of broadband dielectric spectroscopy, differential scanning calorimetry, X-ray scattering, and neutron scattering techniques, the research explores the glass transition phenomena and relaxation processes in these materials. HOT6, featuring ester linkages, exhibits distinct dynamic behavior compared to HAT6, including two separate glass transitions indicated by the α1- and α2-relaxation found by dielectric spectroscopy which are assigned to the glassy dynamics of the alkyl side chain in the intercolumnar space and that of the columns, respectively. The study reveals that the ester group in HOT6 leads to increased molecular rigidity and altered packing in the intercolumnar space, as evidenced by X-ray scattering and the vibrational density of states. Neutron scattering confirms localized methyl group rotations and a further relaxation process which relates to the γ-relaxation revealed by dielectric spectroscopy. The findings contribute to a deeper understanding of glassy dynamics in partially ordered systems and highlight the influence of molecular architecture on relaxation behavior in DLCs.
Clinically, palpation is one of the important diagnostic methods to assess tumor malignancy. In laboratory research, it is well accepted that the bulk stiffness of the tumor and the surrounding tissue is closely correlated with the malignant state of the tumor. Here, we postulate that, in addition to tumor stiffness, tumor viscoelasticity – the fact that tumor tissue takes time to bounce back after compression, can also be used to evaluate the tumor malignancy state. In this work, we characterized the viscoelastic properties of tumor spheroids using a recently developed microfluidic compression device by quantifying their relaxation dynamics upon load removal. Tumor spheroids were made using breast tumor cells spanning various malignancy levels; non-tumorigenic epithelial (MCF10A), moderately malignant tumor (MCF7) and triple negative metastatic tumor (MDA-MB-231) cell line. Spheroids embedded within a 3D extracellular matrix were periodically compressed, and their strain responses were recorded using microscopic imaging. Our results revealed that the measured strain relaxation dynamics can be successfully described by a modified power law model, demonstrated that non-tumorigenic tumor spheroids were more elastic, exhibited shorter relaxation time and less plasticity than those of tumorigenic spheroids. This work highlights that viscoelastic properties in addition to bulk stiffness of the tumor spheroids can serve as a complementary mechanical biomarker of tumor malignancy and demonstrate the validity of a modified power law model for the mechanical characterization of a living tissue.
Nanoparticles (NPs) demonstrate considerable potential in medical applications, including targeted drug delivery and diagnostic probes. However, their efficacy depends on their ability to navigate through the complex biological environments inside living organisms. In such environments, NPs interact with a dense mixture of biomolecules, which can reduce their mobility and hinder diffusion. Understanding the factors influencing NP diffusion in these environments is key to improving nanomedicine design and predicting toxicological effects. In this study, we propose a computational approach to model NP diffusion in crowded environments. We introduce a mesoscale model that accounts for the combined effects of the protein corona (PC) and the crowded medium on NP mobility. By including volume-exclusion interactions and modelling the PC both explicitly and implicitly, we identify key macromolecular descriptors that affect NP diffusion. Our results show that the morphology of the PC can significantly affect the diffusion of NPs, and the roles of the occupied volume fraction and the size ratio between tracers and crowders are analysed. The results also show that approximating large macromolecular assemblies with a hydrodynamic single-sphere model leads to inexact diffusion estimates. To overcome the limitations of single-sphere representations, a strategy for an accurate parameterization of NP–PC systems using a single-sphere model is presented and the validity and limitations of the model are discussed.
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