ResearchPad - applied-physical-sciences https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Fibroblast rejuvenation by mechanical reprogramming and redifferentiation]]> https://www.researchpad.co/article/elastic_article_8266 Over the course of the aging process, fibroblasts lose contractility, leading to reduced connective-tissue stiffness. A promising therapeutic avenue for functional rejuvenation of connective tissue is reprogrammed fibroblast replacement, although major hurdles still remain. Toward this, we recently demonstrated that the laterally confined growth of fibroblasts on micropatterned substrates induces stem-cell-like spheroids. In this study, we embedded these partially reprogrammed spheroids in collagen-I matrices of varying densities, mimicking different three-dimensional (3D) tissue constraints. In response to such matrix constraints, these spheroids regained their fibroblastic properties and sprouted to form 3D connective-tissue networks. Interestingly, we found that these differentiated fibroblasts exhibit reduced DNA damage, enhanced cytoskeletal gene expression, and actomyosin contractility. In addition, the rejuvenated fibroblasts show increased matrix protein (fibronectin and laminin) deposition and collagen remodeling compared to the parental fibroblast tissue network. Furthermore, we show that the partially reprogrammed cells have comparatively open chromatin compaction states and may be more poised to redifferentiate into contractile fibroblasts in 3D-collagen matrix. Collectively, our results highlight efficient fibroblast rejuvenation through laterally confined reprogramming, which has important implications in regenerative medicine.

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<![CDATA[High-throughput, combinatorial synthesis of multimetallic nanoclusters]]> https://www.researchpad.co/article/Nf0c9e310-00e1-42ea-83d8-4bfb172f41d1

Significance

Multielement nanomaterials hold great promise for various applications due to their widely tunable surface chemistry, yet it remains challenging to efficiently study this multidimensional space. Conventional approaches are typically slow and depend on serendipity, while a robust and general synthesis is still lacking among increasingly complex compositions. We report a high-throughput technique for combinatorial compositional design (formulation in solution phases) and rapid synthesis (within seconds) of ultrafine multimetallic nanoclusters with a homogeneous alloy structure. We synthesized and screened the PtPdRhRuIrFeCoNi compositional space using scanning droplet cell electrochemistry, with two promising catalysts quickly identified and further verified in a rotating disk setup. The reported high-throughput approach establishes a facile and reliable pipeline to significantly accelerate material discovery in multimetallic nanomaterials.

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<![CDATA[Reply to Santín et al.: Viscoelastic retardant fluids enable treatments to prevent wildfire on landscapes subject to routine ignitions]]> https://www.researchpad.co/article/Nba760fa8-acfa-4830-9f36-68974e773e57 ]]> <![CDATA[Bioinspired underwater locomotion of light-driven liquid crystal gels]]> https://www.researchpad.co/article/N41eef6d8-7e8f-47f7-a447-ae50b833ba1f

Significance

Untethered dynamic shape programming and control of soft materials have significant applications in technologies such as soft robots, medical devices, organ-on-a-chip, and optical devices. Here, we present a solution to remotely actuate and move soft materials underwater in a fast, efficient, and controlled manner using photoresponsive liquid crystal gels (LCGs). LCG constructs with engineered molecular alignment show a low and sharp phase-transition temperature and experience considerable density reduction by light exposure, thereby allowing rapid and reversible shape changes. We demonstrate different modes of underwater locomotion, such as crawling, walking, jumping, and swimming, by localized and time-varying illumination of LCGs. The diverse locomotion modes of smart LCGs can provide a new toolbox for designing efficient light-fueled soft robots in fluid-immersed media.

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<![CDATA[No evidence of suitability of prophylactic fluids for wildfire prevention at landscape scales]]> https://www.researchpad.co/article/N96747a8d-8865-4108-8a87-40f41da7bbfa ]]> <![CDATA[Intermediate states of molecular self-assembly from liquid-cell electron microscopy]]> https://www.researchpad.co/article/Nea75eb2e-c25a-4a0c-a62a-aea6e19545c8

Significance

Graphene liquid-cell electron microscopy reveals intermediate states of self-assembly—in this example, DNA when single strands form double helices. Molecules are observed for up to minutes at a time without apparent beam damage when electron energy and electron dose are low. Simultaneous in situ single-molecule imaging of conformational adaptations and motion gives more comprehensive understanding of self-assembly successes, failures, and error-producing mechanisms, confirming some earlier predictions and also presenting surprises. Loop intermediates were observed to facilitate error correction. Hybridization events accompany enhanced translational mobility and mechanistically specific persistent rotation. The information obtained goes beyond that from other single-molecule methods.

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<![CDATA[Magnetic control of graphitic microparticles in aqueous solutions]]> https://www.researchpad.co/article/5c8015c1d5eed0c484a9faae

Significance

This paper presents the magnetic transport of diamagnetic graphite microparticles in water solutions. Given the dominance of viscous drag forces at the microscale, moving a microparticle that is submerged in liquid is comparably as hard as moving a macroparticle within dense honey. While diamagnetism is a weak magnetic property, for graphite it can be exploited to generate useful transport in liquid. The contactless magnetic control of biocompatible micrographite, together with graphite’s unique physical properties, opens up possibilities for applications in sensing, analysis, synthesis, and diagnosis in chemistry, biology, medicine, and physics.

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<![CDATA[Jump rope vortex in liquid metal convection]]> https://www.researchpad.co/article/5c26b3add5eed0c484760c62

Significance

The large-scale circulation (LSC) is the key dynamical feature of turbulent thermal convection. It is the underlying structure that shapes the appearance of geo- and astrophysical systems, such as the solar granulation or cloud streets, and the cornerstone of theoretical models. Our laboratory-numerical experiments reveal that the LSC can perform a fully 3D motion resembling a twirling jump rope. The discovery of this LSC mode implies that the currently accepted paradigm of a quasi-planar oscillating LSC needs to be augmented. Moreover, it provides an important link between studies in confined geometries used in experiments and simulations and the effectively unconfined fluid layers in natural settings where an agglomeration of LSCs forms larger patterns.

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<![CDATA[Mesoscale structure, mechanics, and transport properties of source rocks’ organic pore networks]]> https://www.researchpad.co/article/5c26b521d5eed0c484764c83

Significance

In source rocks, natural hydrocarbons are generated from organic matter dispersed in a fine-grained mineral matrix. The potential recovery of hydrocarbons is therefore influenced by the geometry of the organic hosted porous networks. Here, the three-dimensional structures of such networks are revealed using electron tomography with a subnanometer resolution. The reconstructions are first characterized in terms of morphology and topology and then used to build a multiscale simulation tool to study the mechanics and the transport properties of confined fluids. Our results offer evidence of the prevalent role of connected nanopores, which subsequently constitutes a material limit for long-term hydrocarbon production.

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<![CDATA[Differential growth and shape formation in plant organs]]> https://www.researchpad.co/article/5c26b51ad5eed0c484764b2d

Significance

Plant leaves and flower petals in nature exhibit a wide variety of complex 3D shapes. Formation of these shapes has largely been studied from genetic and biomolecular viewpoints, overlooking contributions from biophysical factors such as mechanical stress and deformation. By means of computational simulations and quantitative analyses of the growth strains in live plant organs, we develop fundamental mechanistic insights into how nature invokes mechanics in the evolution of four commonly found shapes in plant organs by differential growth. We also demonstrate how these common shapes can be synthetically reproduced in hydrogel using this mechanistic understanding. Our study provides a broad scientific framework for rationalizing plant organ morphogenesis, but also provides pathways for generating bioinspired 3D architectures in soft materials.

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